feat: add screenshot gallery, theme selector, and 4 new curated themes

- Add comprehensive screenshot gallery in README.md and docs/GALLERY.md
  showcasing all desktop features, menus, and control panels
- Clean and sanitize screenshots (no private work projects or processes)
- Add 4 curated themes with accurate color palettes and btop themes:
  * Pirna (Bernardo Bellotto classic art)
  * Nordic Frost (Arctic aurora and mountain cliff)
  * Monolith (Sci-fi alien coast and bioluminescent cyan)
  * Dragon Fire (Dark fantasy gothic siege and fiery coral embers)
- Enhance theme selector in rice-theme and rice-menu with live grid thumbnails
- Add super + shift + t shortcut for instant visual theme switching
- Make wallpaper lookup robust across repo and user directories

themes/dragon-fire/btop.theme

@@ -0,0 +1,53 @@
+# btop - Dragon Fire
+theme[main_bg]=""
+theme[main_fg]="#faece8"
+theme[title]="#faece8"
+theme[hi_fg]="#f5796b"
+theme[selected_bg]="#422834"
+theme[selected_fg]="#f5796b"
+theme[inactive_fg]="#96747b"
+theme[graph_text]="#dec7c1"
+theme[meter_bg]="#24151b"
+theme[proc_misc]="#6fb0a6"
+
+theme[cpu_box]="#573544"
+theme[mem_box]="#573544"
+theme[net_box]="#573544"
+theme[proc_box]="#573544"
+theme[div_line]="#573544"
+
+theme[temp_start]="#7ea66b"
+theme[temp_mid]="#e89f5a"
+theme[temp_end]="#e05853"
+
+theme[cpu_start]="#e89f5a"
+theme[cpu_mid]="#f5796b"
+theme[cpu_end]="#dc82a6"
+
+theme[free_start]="#415753"
+theme[free_mid]="#6fb0a6"
+theme[free_end]="#85c7bd"
+
+theme[cached_start]="#476085"
+theme[cached_mid]="#688dc4"
+theme[cached_end]="#82a5dc"
+
+theme[available_start]="#8c5d31"
+theme[available_mid]="#e89f5a"
+theme[available_end]="#f5b373"
+
+theme[used_start]="#8c332e"
+theme[used_mid]="#e05853"
+theme[used_end]="#ff4a5d"
+
+theme[download_start]="#8c473b"
+theme[download_mid]="#f5796b"
+theme[download_end]="#f5b373"
+
+theme[upload_start]="#80415a"
+theme[upload_mid]="#c76d91"
+theme[upload_end]="#dc82a6"
+
+theme[process_start]="#7ea66b"
+theme[process_mid]="#94bc80"
+theme[process_end]="#e89f5a"

themes/dragon-fire/colors.toml

@@ -0,0 +1,55 @@
+# Dragon Fire - sampled from wallpapers/dragon-fire.jpg
+name = "Dragon Fire"
+mode = "dark"
+wallpaper = "dragon-fire.jpg"
+
+# --- surfaces, darkest to lightest ---
+bg        = "#140b0f"
+bg_alt    = "#1a0f14"
+surface   = "#24161c"
+overlay   = "#321e27"
+selection = "#422834"
+border    = "#573544"
+
+# --- text ---
+fg     = "#faece8"
+fg_alt = "#dec7c1"
+dim    = "#96747b"
+muted  = "#402632"
+
+# --- roles ---
+accent     = "#f5796b"
+accent_alt = "#c94f42"
+urgent     = "#ff4a5d"
+
+# --- named colours (ANSI 1-6) and their bright twins (9-14) ---
+red     = "#e05853"
+green   = "#7ea66b"
+yellow  = "#e89f5a"
+blue    = "#688dc4"
+magenta = "#c76d91"
+cyan    = "#6fb0a6"
+
+bright_red     = "#f26d68"
+bright_green   = "#94bc80"
+bright_yellow  = "#f5b373"
+bright_blue    = "#82a5dc"
+bright_magenta = "#dc82a6"
+bright_cyan    = "#85c7bd"
+
+# --- translucency ---
+alpha     = "0.78"
+alpha_hex = "c7"
+
+# --- shape and type ---
+font          = "JetBrainsMono Nerd Font"
+font_size     = "11"
+radius        = "12"
+radius_small  = "8"
+border_width  = "1"
+window_border = "2"
+gap           = "10"
+icon_theme    = "Papirus-Dark"
+gtk_theme     = "Adwaita-dark"
+cursor_theme  = "Bibata-Modern-Classic"
+cursor_size   = "20"

themes/monolith/btop.theme

@@ -0,0 +1,53 @@
+# btop - Monolith
+theme[main_bg]=""
+theme[main_fg]="#dff5f0"
+theme[title]="#dff5f0"
+theme[hi_fg]="#4ec7b0"
+theme[selected_bg]="#284452"
+theme[selected_fg]="#4ec7b0"
+theme[inactive_fg]="#6e9ca0"
+theme[graph_text]="#bee5dd"
+theme[meter_bg]="#14242c"
+theme[proc_misc]="#4ec7b0"
+
+theme[cpu_box]="#355b6c"
+theme[mem_box]="#355b6c"
+theme[net_box]="#355b6c"
+theme[proc_box]="#355b6c"
+theme[div_line]="#355b6c"
+
+theme[temp_start]="#56bf9a"
+theme[temp_mid]="#d6b565"
+theme[temp_end]="#d95f6e"
+
+theme[cpu_start]="#3d9ed6"
+theme[cpu_mid]="#4ec7b0"
+theme[cpu_end]="#69e0c9"
+
+theme[free_start]="#2e5461"
+theme[free_mid]="#4ec7b0"
+theme[free_end]="#69e0c9"
+
+theme[cached_start]="#286387"
+theme[cached_mid]="#3d9ed6"
+theme[cached_end]="#57b4eb"
+
+theme[available_start]="#7d6a36"
+theme[available_mid]="#d6b565"
+theme[available_end]="#e8ca7d"
+
+theme[used_start]="#823742"
+theme[used_mid]="#d95f6e"
+theme[used_end]="#e66075"
+
+theme[download_start]="#286991"
+theme[download_mid]="#3d9ed6"
+theme[download_end]="#57b4eb"
+
+theme[upload_start]="#624975"
+theme[upload_mid]="#9b78b5"
+theme[upload_end]="#b390cd"
+
+theme[process_start]="#56bf9a"
+theme[process_mid]="#6ad9b2"
+theme[process_end]="#d6b565"

themes/monolith/colors.toml

@@ -0,0 +1,55 @@
+# Monolith - sampled from wallpapers/monolith.png
+name = "Monolith"
+mode = "dark"
+wallpaper = "monolith.png"
+
+# --- surfaces, darkest to lightest ---
+bg        = "#0a1317"
+bg_alt    = "#0f1b20"
+surface   = "#16262e"
+overlay   = "#1e343e"
+selection = "#284452"
+border    = "#355b6c"
+
+# --- text ---
+fg     = "#dff5f0"
+fg_alt = "#bee5dd"
+dim    = "#6e9ca0"
+muted  = "#264349"
+
+# --- roles ---
+accent     = "#4ec7b0"
+accent_alt = "#369986"
+urgent     = "#e66075"
+
+# --- named colours (ANSI 1-6) and their bright twins (9-14) ---
+red     = "#d95f6e"
+green   = "#56bf9a"
+yellow  = "#d6b565"
+blue    = "#3d9ed6"
+magenta = "#9b78b5"
+cyan    = "#4ec7b0"
+
+bright_red     = "#e67381"
+bright_green   = "#6ad9b2"
+bright_yellow  = "#e8ca7d"
+bright_blue    = "#57b4eb"
+bright_magenta = "#b390cd"
+bright_cyan    = "#69e0c9"
+
+# --- translucency ---
+alpha     = "0.76"
+alpha_hex = "c2"
+
+# --- shape and type ---
+font          = "JetBrainsMono Nerd Font"
+font_size     = "11"
+radius        = "12"
+radius_small  = "8"
+border_width  = "1"
+window_border = "2"
+gap           = "10"
+icon_theme    = "Papirus-Dark"
+gtk_theme     = "Adwaita-dark"
+cursor_theme  = "Bibata-Modern-Classic"
+cursor_size   = "20"

themes/nordic-frost/btop.theme

@@ -0,0 +1,53 @@
+# btop - Nordic Frost
+theme[main_bg]=""
+theme[main_fg]="#e8eff7"
+theme[title]="#e8eff7"
+theme[hi_fg]="#68a6d4"
+theme[selected_bg]="#2d3e54"
+theme[selected_fg]="#68a6d4"
+theme[inactive_fg]="#7d93ab"
+theme[graph_text]="#c8d8e8"
+theme[meter_bg]="#182330"
+theme[proc_misc]="#5ec0be"
+
+theme[cpu_box]="#3c516c"
+theme[mem_box]="#3c516c"
+theme[net_box]="#3c516c"
+theme[proc_box]="#3c516c"
+theme[div_line]="#3c516c"
+
+theme[temp_start]="#56b88e"
+theme[temp_mid]="#e5a840"
+theme[temp_end]="#d45b65"
+
+theme[cpu_start]="#5a98cf"
+theme[cpu_mid]="#68a6d4"
+theme[cpu_end]="#ba94ce"
+
+theme[free_start]="#3d5a59"
+theme[free_mid]="#5ec0be"
+theme[free_end]="#74d4d2"
+
+theme[cached_start]="#41698e"
+theme[cached_mid]="#5a98cf"
+theme[cached_end]="#78b4e8"
+
+theme[available_start]="#8f6929"
+theme[available_mid]="#e5a840"
+theme[available_end]="#f2be5c"
+
+theme[used_start]="#853940"
+theme[used_mid]="#d45b65"
+theme[used_end]="#de505b"
+
+theme[download_start]="#3b6994"
+theme[download_mid]="#5a98cf"
+theme[download_end]="#78b4e8"
+
+theme[upload_start]="#6e507d"
+theme[upload_mid]="#a47eb8"
+theme[upload_end]="#ba94ce"
+
+theme[process_start]="#56b88e"
+theme[process_mid]="#68cca0"
+theme[process_end]="#e5a840"

themes/nordic-frost/colors.toml

@@ -0,0 +1,55 @@
+# Nordic Frost - sampled from wallpapers/nordic-frost.jpg
+name = "Nordic Frost"
+mode = "dark"
+wallpaper = "nordic-frost.jpg"
+
+# --- surfaces, darkest to lightest ---
+bg        = "#0d131a"
+bg_alt    = "#131b24"
+surface   = "#1b2533"
+overlay   = "#243244"
+selection = "#2d3e54"
+border    = "#3c516c"
+
+# --- text ---
+fg     = "#e8eff7"
+fg_alt = "#c8d8e8"
+dim    = "#7d93ab"
+muted  = "#34455a"
+
+# --- roles ---
+accent     = "#68a6d4"
+accent_alt = "#4478a3"
+urgent     = "#de505b"
+
+# --- named colours (ANSI 1-6) and their bright twins (9-14) ---
+red     = "#d45b65"
+green   = "#56b88e"
+yellow  = "#e5a840"
+blue    = "#5a98cf"
+magenta = "#a47eb8"
+cyan    = "#5ec0be"
+
+bright_red     = "#e26c75"
+bright_green   = "#68cca0"
+bright_yellow  = "#f2be5c"
+bright_blue    = "#78b4e8"
+bright_magenta = "#ba94ce"
+bright_cyan    = "#74d4d2"
+
+# --- translucency ---
+alpha     = "0.76"
+alpha_hex = "c2"
+
+# --- shape and type ---
+font          = "JetBrainsMono Nerd Font"
+font_size     = "11"
+radius        = "12"
+radius_small  = "8"
+border_width  = "1"
+window_border = "2"
+gap           = "10"
+icon_theme    = "Papirus-Dark"
+gtk_theme     = "Adwaita-dark"
+cursor_theme  = "Bibata-Modern-Classic"
+cursor_size   = "20"

themes/pirna/btop.theme

@@ -0,0 +1,53 @@
+# btop - Pirna, sampled from Bernardo Bellotto's Pirna from Sonnenstein Fortress
+theme[main_bg]=""
+theme[main_fg]="#ede8dc"
+theme[title]="#ede8dc"
+theme[hi_fg]="#78a6ba"
+theme[selected_bg]="#333d40"
+theme[selected_fg]="#78a6ba"
+theme[inactive_fg]="#828c8a"
+theme[graph_text]="#cdc7b7"
+theme[meter_bg]="#1f2527"
+theme[proc_misc]="#6e9e98"
+
+theme[cpu_box]="#445053"
+theme[mem_box]="#445053"
+theme[net_box]="#445053"
+theme[proc_box]="#445053"
+theme[div_line]="#445053"
+
+theme[temp_start]="#7b9456"
+theme[temp_mid]="#cca056"
+theme[temp_end]="#b8543f"
+
+theme[cpu_start]="#658ea4"
+theme[cpu_mid]="#78a6ba"
+theme[cpu_end]="#ba94a8"
+
+theme[free_start]="#465856"
+theme[free_mid]="#6e9e98"
+theme[free_end]="#84b5ae"
+
+theme[cached_start]="#4f6e82"
+theme[cached_mid]="#658ea4"
+theme[cached_end]="#78a6ba"
+
+theme[available_start]="#7a6238"
+theme[available_mid]="#cca056"
+theme[available_end]="#dfb56c"
+
+theme[used_start]="#74372a"
+theme[used_mid]="#b8543f"
+theme[used_end]="#c45842"
+
+theme[download_start]="#466275"
+theme[download_mid]="#658ea4"
+theme[download_end]="#78a6ba"
+
+theme[upload_start]="#695160"
+theme[upload_mid]="#a17b8f"
+theme[upload_end]="#ba94a8"
+
+theme[process_start]="#7b9456"
+theme[process_mid]="#8ea559"
+theme[process_end]="#cca056"

themes/pirna/colors.toml

@@ -0,0 +1,59 @@
+# Pirna - sampled from wallpapers/bellotto-pirna.jpg (Bernardo Bellotto, 1750s).
+# Every surface (bspwm, polybar, rofi, dunst, eww, st, kitty, GTK, btop,
+# xsecurelock, starship) is rendered from these keys by `rice-theme`.
+# Colour values must be #rrggbb; templates add alpha where they need it.
+
+name = "Pirna"
+mode = "dark"
+wallpaper = "bellotto-pirna.jpg"
+
+# --- surfaces, darkest to lightest ---
+bg        = "#121516"
+bg_alt    = "#181d1e"
+surface   = "#212729"
+overlay   = "#2b3336"
+selection = "#333d40"
+border    = "#445053"
+
+# --- text ---
+fg     = "#ede8dc"
+fg_alt = "#cdc7b7"
+dim    = "#828c8a"
+muted  = "#3c4648"
+
+# --- roles ---
+accent     = "#78a6ba"
+accent_alt = "#547e8f"
+urgent     = "#c45842"
+
+# --- named colours (ANSI 1-6) and their bright twins (9-14) ---
+red     = "#b8543f"
+green   = "#7b9456"
+yellow  = "#cca056"
+blue    = "#658ea4"
+magenta = "#a17b8f"
+cyan    = "#6e9e98"
+
+bright_red     = "#c45842"
+bright_green   = "#8ea559"
+bright_yellow  = "#dfb56c"
+bright_blue    = "#78a6ba"
+bright_magenta = "#ba94a8"
+bright_cyan    = "#84b5ae"
+
+# --- translucency: bar, popups, menus, notifications and terminals all use it ---
+alpha     = "0.78"
+alpha_hex = "c7"
+
+# --- shape and type, shared by every popup, menu and toast ---
+font          = "JetBrainsMono Nerd Font"
+font_size     = "11"
+radius        = "12"
+radius_small  = "8"
+border_width  = "1"
+window_border = "2"
+gap           = "10"
+icon_theme    = "Papirus-Dark"
+gtk_theme     = "Adwaita-dark"
+cursor_theme  = "Bibata-Modern-Classic"
+cursor_size   = "20"