feat(anime): add anime browser powered by Aniyomi extensions

- Add `subminer anime` / `--anime` and a tray entry to open a browser that searches installed Aniyomi extension sources, shows cover art and episodes, and plays into mpv with overlay/mining attached
- Add an Extensions tab to add repos and install/update/remove sources, and per-source settings for sources needing config
- Support searching all sources at once with streaming, per-source results and status
- Prefer Japanese audio/subtitle tracks from the source and keep the primary subtitle slot reserved for Japanese
- Fix window/tray/Dock handling so the browser and mpv can be switched between without quitting the app or losing the Dock icon
- Add anime.repos, anime.extensionsDir, anime.preferredQuality config keys (no bundled repos or discovery)

src/animeui/dom.ts

@@ -0,0 +1,13 @@
+/** Small helpers shared by the anime browser's panels. */
+
+export function el<T extends HTMLElement>(id: string): T {
+  const node = document.getElementById(id);
+  if (!node) throw new Error(`Missing element #${id}`);
+  return node as T;
+}
+
+export function describe(error: unknown): string {
+  const message = error instanceof Error ? error.message : String(error);
+  // Electron wraps handler errors; keep only the useful tail.
+  return message.replace(/^Error invoking remote method '[^']+':\s*/, '').replace(/^Error:\s*/, '');
+}