feat: Phase N power-user surface (terminal, palette, per-item, sort, url-templates)

- Built-in yt-dlp terminal: src/main/terminal.ts streams raw yt-dlp runs
  (binary fixed, gated on customCommandEnabled), new TerminalView + sidebar tab
- Command palette (Ctrl/Cmd+K), portal-free CommandPalette.tsx wired in App
- Per-playlist-item editing: per-row video/audio toggle + All video/All audio
  batch; addPlaylist enqueues via addMany with per-item kind
- Weighted format sorting: DownloadOptions.formatSort -> raw -S (overrides codec)
- URL-regex template auto-matching: CommandTemplate.urlPattern + selectExtraArgs
  matchesUrl, threaded through resolveExtraArgs; field in TemplateManager

typecheck + test (192) + electron-vite build all clean. Roadmap: Phase N COMPLETE.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/main/templates.ts

@@ -36,10 +36,13 @@ function save(templates: CommandTemplate[]): void {
 }
 
 function sanitize(t: CommandTemplate): CommandTemplate {
+  const urlPattern = typeof t.urlPattern === 'string' ? t.urlPattern.trim() : ''
   return {
     id: String(t.id),
     name: (t.name ?? '').trim() || 'Untitled command',
-    args: (t.args ?? '').trim()
+    args: (t.args ?? '').trim(),
+    // Only persist a urlPattern when one was provided, keeping older files clean.
+    ...(urlPattern ? { urlPattern } : {})
   }
 }