Give the desktop real themes, video wallpapers, and honest titlebars

Appearance now opens on Themes: light and dark side by side, each
remembering its own choice, over galleries of ten shipped themes —
Tokyo Moon and Day joined by Moon Rose, Catppuccin, Nord, Gruvbox and
Everforest in both modes. A theme is a complete palette: the catalog
lives in themes.json, Theme.qml reads every color token from the
active record, and one render pipeline carries it to kitty, tmux,
btop, GTK, Vicinae, Firefox's chrome, and the lock screen. The Theme
editor builds new ones from four wells — wheel, hex, or eyedropper —
with derived surfaces, a saturation slider, debounced fine-tune, and
effects that save with the theme. Custom edits finally keep GNOME's
accent, kitty's border, and hyprlock in sync.

Wallpapers can be video: mpvpaper per output, hardware-decoded, muted
and looped, supervised and respawned. Panama owns the pausing — games,
battery, and a bar pill for right now — because the compositor
rebuilds full-screen blur for every frame a video wallpaper draws.
The lock screen gets a still frame.

Titlebars stop lying. GNOME apps get close-only on your chosen side,
the maximize and double-click settings are gone, the Settings window
obeys the same rules, and its titlebar can be turned off entirely.
Typography becomes five labeled dropdowns instead of a wall of
samples.

Contracts updated and written throughout (165 now); per the redesign
workflow none were executed — the full sweep runs once at the end.

Claude-Session: https://claude.ai/code/session_01Ms2FbjQy31TVf3CEvQhGM8

config/dot/quickshell/modules/settings/DesktopPreview.qml

@@ -50,13 +50,13 @@ Rectangle {
 
     // Stands in for the wallpaper. Static: an animated gradient here would
     // repaint forever behind a settings page.
-    // Follows the color scheme. A preview that stays dark while the shell
-    // around it is light does not read as "your desktop" -- it reads as a
-    // screenshot of someone else's.
+    // Derived from the active theme's palette rather than fixed hexes, so the
+    // preview re-grounds itself when a theme is chosen -- a Gruvbox desktop
+    // whose preview stayed Tokyo-blue would read as someone else's.
     gradient: Gradient {
         orientation: Gradient.Vertical
-        GradientStop { position: 0.0; color: Theme.dark ? "#2b3050" : "#b9c0dd" }
-        GradientStop { position: 1.0; color: Theme.dark ? "#241f33" : "#cbbcd4" }
+        GradientStop { position: 0.0; color: Theme.mix(Theme.bgHighlight, Theme.accent, 0.12) }
+        GradientStop { position: 1.0; color: Theme.mix(Theme.bgDark, Theme.accentSecondary, 0.10) }
     }
 
     // The bar, so the preview reads as this desktop and not a generic one.
@@ -209,7 +209,8 @@ Rectangle {
             shadowEnabled: true
             shadowColor: win.focused && root.glowOn
                 ? Theme.alpha(Theme.accent, 0.5)
-                : Theme.alpha(Theme.dark ? "#15161e" : "#6172b0", Theme.dark ? 0.85 : 0.45)
+                : Theme.alpha(Theme.dark ? Theme.mix(Theme.bgDark, "#000000", 0.35) : Theme.fgDim,
+                    Theme.dark ? 0.85 : 0.45)
             shadowBlur: win.focused && root.glowOn
                 ? Math.min(1.0, root.px(root.glowRange) / 12)
                 : Math.min(1.0, root.px(root.shadowRange) / 24)