Notch theme switcher + keybind for the wallpapers tab

[Palccod]

What

Two additions to the notch's Wallpapers tab, built as one feature:

A keybind for the tab. New ruixen.notch toggleWallpapers IPC — same shape as toggleDashboard (a closed notch opens straight onto the Wallpapers tab, an open one just closes). The recommended keybind is SUPER + CTRL + SPACE; note that key is stock Omarchy's Background switcher, so install.sh keeps its existing "key already bound — leaving it untouched" behavior and prints the collision for manual unbind-first setup. docs/KEYBINDS.md shows the hl.unbind + o.bind pair.

A theme switcher in the tab. A WALLPAPER SWITCHER / THEME SWITCHER segmented control above the search box (direct request: "the 2 options will be above the search box, so theme will say search themes..."). Theme mode lists every installed Omarchy theme with real preview tiles and clicking one runs the real omarchy-theme-set — the same front door as Omarchy's own theme menu, after stopping any playing video/GIF with a fresh generation. The search placeholder follows the mode ("Search themes..." / "Search wallpapers..."); switching modes clears the shared search box.

How

• Theme discovery lives in a new shipped bars/widgets/ruixen.notch/list-themes.sh — same extraction-so-tests-cannot-drift rationale as list-wallpapers.sh ([P2] Extract wallpaper discovery into shared production code so tests cannot drift #17). It replicates omarchy-theme-switcher's own preview rules (read directly, not guessed): preview.{png,jpg,jpeg,webp,gif,bmp} at the theme's top level, else the first sorted backgrounds/ image, else fall back to the same-name system theme. User themes (dirs or symlinks) union system themes (dirs), user copy winning — the same two-source resolution omarchy-theme-set itself accepts.
• Grid fill: the theme grid sizes itself to the panel — as many ≥170px-minimum columns as fit, cells stretched to consume the row (tiles grow 160→180px, same 10px gap rhythm as the wallpaper side), with the indivisible remainder centered so left/right margins are equal instead of a dead strip on the right (direct request). Preview sourceSize tracks the rendered tile so larger tiles stay sharp. The launcher's own wallpaper card is deliberately unchanged — the keybind targets the notch tab, and that copy stays a pure picker (its sync comment says so now).
• Safety: applyTheme whitelist-validates the theme name against ^[A-Za-z0-9][A-Za-z0-9_-]*$ before it reaches a fixed-argv Process; labels render Text.PlainText; theme names come from directory basenames that omarchy-theme-set re-normalizes itself.

Tests

New tests/notch-theme-switcher.sh (26 checks, registered in run-all.sh): runs the real list-themes.sh against a fixture tree (preview.png, backgrounds-only, user-falls-back-to-system, user-over-system precedence, dot-dir skip, title-casing) and grep-pins the QML/IPC/installer wiring (segmented control placement above the search box, placeholder swap, whitelist + omarchy-theme-set routing, stop-with-fresh-generation, toggleWallpapers, keybind recommendation + dry-run preview). Full run-all.sh green.

Live-verified on a real omarchy restart shell: keybind registered (omarchy menu keybindings shows SUPER CTRL + SPACE → Ruixen wallpapers), toggle IPC opens the tab, theme grid renders all 25 installed themes with previews, and the apply path was exercised end-to-end against a stubbed omarchy-theme-set on PATH (optimistic CURRENT highlight, then re-synced from theme.name after the post-set refresh) — real themes untouched.