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

tests/quickshell/lock-screen-settings-contract

@@ -46,14 +46,30 @@ for key in lockBackgroundMode lockBlurLevel lockShowClock lockShowDate lockShowU
         || fail "$key was duplicated onto Power or Privacy"
 done
 
-python3 - "$appearance" <<'PY' || fail 'Lock screen card is not between Background and Shell typography'
+# The lock screen is the third card of the Background tab, after the still and
+# video wallpaper cards. It belongs there because it is a picture of the
+# desktop: the background is what it blurs, and the card above is what it
+# takes a still frame of.
+python3 - "$appearance" <<'PY' || fail 'the Lock screen card is not the last card of the Background tab'
+import re
 import sys
 
 text = open(sys.argv[1], encoding="utf-8").read()
-background = text.index('title: "Background"')
-lock = text.index('title: "Lock screen"')
-typography = text.index('title: "Shell typography"')
-raise SystemExit(0 if background < lock < typography else 1)
+order = ['title: "Background"', 'title: "Video playback"', 'title: "Lock screen"']
+positions = []
+for title in order:
+    if title not in text:
+        raise SystemExit(f"Appearance has no {title} card")
+    positions.append(text.index(title))
+if positions != sorted(positions):
+    raise SystemExit("the Background tab's cards are out of order")
+
+# Each of the three is gated on the same tab, so none of them strands the
+# others on a page nobody opens.
+for card in re.findall(r'SettingsCard \{(.*?)\n    \}', text, re.S):
+    for title in order:
+        if title in card and 'root.tab === "background"' not in card:
+            raise SystemExit(f"the {title} card is not on the Background tab")
 PY
 
 qs_for_harness() {