feat(youtube): add YouTube browser window and Whisper subtitle source

- Add `subminer youtube`/`yt` and tray "Browse YouTube" window that plays or queues picked videos in mpv
- Add `youtube.subtitleSource` (`youtube` | `whisper`) to transcribe YouTube audio via subtitle generation
- Allow the subtitle generation modal on YouTube videos
- Pick the real Japanese track over machine-translated ones and fall back to yt-dlp on HTTP 429
- Remove legacy launcher youtubeSubgen/whisper/AI args and `--youtube-mode`
- Fix EPIPE crash when the launching terminal is closed with Ctrl+C
- Thin media timing review handles with orange original-boundary bars
- Update docs and change fragments

src/cli/args.ts

@@ -7,7 +7,6 @@ export interface CliArgs {
   launchMpv: boolean;
   launchMpvTargets: string[];
   youtubePlay?: string;
-  youtubeMode?: 'download' | 'generate';
   stop: boolean;
   toggle: boolean;
   toggleVisibleOverlay: boolean;
@@ -16,6 +15,7 @@ export interface CliArgs {
   hachidori: boolean;
   settings: boolean;
   syncWindow: boolean;
+  youtubeBrowser: boolean;
   setup: boolean;
   show: boolean;
   hide: boolean;
@@ -129,7 +129,6 @@ export function parseArgs(argv: string[]): CliArgs {
     launchMpv: false,
     launchMpvTargets: [],
     youtubePlay: undefined,
-    youtubeMode: undefined,
     stop: false,
     toggle: false,
     toggleVisibleOverlay: false,
@@ -138,6 +137,7 @@ export function parseArgs(argv: string[]): CliArgs {
     hachidori: false,
     settings: false,
     syncWindow: false,
+    youtubeBrowser: false,
     setup: false,
     show: false,
     hide: false,
@@ -272,12 +272,6 @@ export function parseArgs(argv: string[]): CliArgs {
     } else if (arg === '--youtube-play') {
       const value = readValue(argv[i + 1]);
       if (value) args.youtubePlay = value;
-    } else if (arg.startsWith('--youtube-mode=')) {
-      const value = arg.split('=', 2)[1];
-      if (value === 'download' || value === 'generate') args.youtubeMode = value;
-    } else if (arg === '--youtube-mode') {
-      const value = readValue(argv[i + 1]);
-      if (value === 'download' || value === 'generate') args.youtubeMode = value;
     } else if (arg === '--launch-mpv') {
       args.launchMpv = true;
       args.launchMpvTargets = argv.slice(i + 1).filter((value) => value && !value.startsWith('--'));
@@ -290,6 +284,7 @@ export function parseArgs(argv: string[]): CliArgs {
     else if (arg === '--hachidori') args.hachidori = true;
     else if (arg === '--settings') args.settings = true;
     else if (arg === '--sync-window') args.syncWindow = true;
+    else if (arg === '--youtube-browser') args.youtubeBrowser = true;
     else if (arg === '--setup') args.setup = true;
     else if (arg === '--show') args.show = true;
     else if (arg === '--hide') args.hide = true;
@@ -574,6 +569,7 @@ export function hasExplicitCommand(args: CliArgs): boolean {
     args.hachidori ||
     args.settings ||
     args.syncWindow ||
+    args.youtubeBrowser ||
     args.setup ||
     args.show ||
     args.hide ||
@@ -654,6 +650,7 @@ export function isStandaloneTexthookerCommand(args: CliArgs): boolean {
     !args.hachidori &&
     !args.settings &&
     !args.syncWindow &&
+    !args.youtubeBrowser &&
     !args.setup &&
     !args.show &&
     !args.hide &&
@@ -727,6 +724,7 @@ export function shouldStartApp(args: CliArgs): boolean {
     args.hachidori ||
     args.settings ||
     args.syncWindow ||
+    args.youtubeBrowser ||
     args.setup ||
     args.copySubtitle ||
     args.copySubtitleMultiple ||
@@ -789,6 +787,7 @@ export function shouldRunDictionarySettingsOnlyStartup(args: CliArgs): boolean {
     !args.togglePrimarySubtitleBar &&
     !args.settings &&
     !args.syncWindow &&
+    !args.youtubeBrowser &&
     !args.show &&
     !args.hide &&
     !args.setup &&