refactor(main): move domains into per-domain assemblies (#309)

* refactor(main): move the YouTube domain into an assembly

createYoutubeAssembly owns the YouTube flow, playback, media cache,
whisper subtitles, primary-subtitle notifications, and the in-app
browser, plus the browser quit-on-close state. main.ts builds it once
where the first YouTube runtime used to be and calls through the result.
Siblings built later are passed as getters or callbacks; tests pin that
construction calls none of them.

* docs(architecture): describe per-domain assemblies

* test(e2e): blank the line before mining the sub-delay cue

The previous test leaves the same cue on screen, so the overlay check
passed before the seek landed and --mine-sentence could read mpv's empty
mid-seek sub-text and skip the card.

* refactor(main): move the Jellyfin domain into an assembly

createJellyfinAssembly owns the Jellyfin composer call, its playback and
remote-progress state, the subtitle cache IO, mpv defaults, and the tray
discovery deps. main.ts builds it where the composer call used to be and
reads state through getActivePlayback/getQuitOnDisconnectArmed.

* refactor(main): move the AniList domain into an assembly

createAnilistAssembly owns the AniList setup and tracking composer calls,
the setup window, the state runtime, and the token, media-guess, in-flight
and attempted-update state they share. main.ts builds it where the setup
composer call used to be and keeps the rate limiter, which the stats
cover-art fetcher also uses.

* refactor(main): move config hot-reload, settings, and sync UI into assemblies

createSettingsAssembly owns config hot-reload and the settings window,
which share the hot-reload-applied handler; main.ts still supplies that
handler's cross-domain deps and the Yomitan deck-name helper.
createSyncAssembly owns the sync window, sync IPC runtime, and auto-sync
scheduler. Both are built where their blocks were; main.ts keeps the
registerHandlers()/start() calls at the same points.

* refactor(main): move dictionary runtimes into assemblies

createDictionariesAssembly owns the JLPT and frequency lookups and their
dictionary-root builders; main.ts still resolves the root paths at the
same point. createCharacterDictionaryAssembly owns the character
dictionary runtime, Yomitan auto-sync, and the portrait and name-candidate
lookups. Both are built where their blocks were; later siblings (Yomitan
profile policy, notifications, OSD, subtitle refresh) come in as getters
or callbacks.

* refactor(main): move overlay modal openers into an assembly

createOverlayModalsAssembly owns the shared open-with-notification helper
and the runtime options, Jimaku, TsukiHime, subtitle generation, session
help, changelog, character dictionary manager, controller, and playlist
browser openers. main.ts builds it where the openers used to live.

* refactor(logger): export the Logger type for assembly deps

The build emits declarations, and the Jellyfin assembly returns the logger
in its tray discovery deps, so tsc needs a nameable Logger type. Assemblies
now Pick from it directly.

e2e/playback.e2e.test.ts

@@ -173,6 +173,12 @@ test(
     const delay = 2;
     await session.mpv.command('set_property', 'sub-delay', delay);
     try {
+      // The previous test leaves this cue on screen, so blank the line first; otherwise the wait
+      // below passes before the seek lands and mining can catch mpv's empty mid-seek sub-text.
+      await session.mpv.command('seek', FIXTURE_CUES[0].start / 2, 'absolute+exact');
+      await overlay.waitFor(`document.getElementById('subtitleRoot').textContent === ''`, {
+        description: 'overlay to clear the line before the first delayed cue',
+      });
       // Past the cue's own end, so the line is only on screen because of the delay.
       await session.mpv.command('seek', cue.end + delay / 2, 'absolute+exact');
       await overlay.waitFor(