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/settings.ts

@@ -101,6 +101,7 @@ function sanitizeOptions(input: unknown): DownloadOptions {
     preferredVideoCodec: VIDEO_CODECS.includes(o.preferredVideoCodec as never)
       ? o.preferredVideoCodec!
       : d.preferredVideoCodec,
+    formatSort: typeof o.formatSort === 'string' ? o.formatSort.trim() : d.formatSort,
     embedSubtitles: bool(o.embedSubtitles, d.embedSubtitles),
     subtitleLanguages:
       typeof o.subtitleLanguages === 'string' && o.subtitleLanguages.trim()