refactor(main): move plugins, session actions and subtitle generation into assemblies (#327)

* refactor(main): build overlay geometry and pointer interaction in the overlay assembly

Inject Electron's screen (and the stats-window promotion) into the overlay geometry and
visible-overlay interaction runtimes so they load under bun test, then construct both in
createOverlayAssembly together with the overlay visibility composer and the mpv subtitle
suppression handlers. Replace the three regex tests that pinned the moved Linux input and
shape code with behaviour tests on the runtimes.

* refactor(main): move the autoplay-ready gate into the playback assembly

The autoplay-ready gate, its post-warm subtitle prime, the current-media tokenization gate and
managed local subtitle selection all read playback state, and playback signals through the
gate, so createPlaybackAssembly now builds them. The overlay reaches the gate through a getter.

Replace the last four regex guards with behaviour tests: the gate holds the release until the
visible overlay has measured the line and ignores untokenized lines during warmup (playback),
cached autoplay priming never paints raw first and the sidebar media path is tagged only after
prefetch loads (priming runtime), and dashboard mining overrides the Hachidori Anki server only
when the proxy is on (stats server runtime). main-wiring.test.ts is now empty and removed.

* refactor(main): move the plugin host, panel and windows into a plugins assembly

* refactor(main): move session action dispatch and renderer mpv commands into an assembly

createSessionActionsAssembly owns the session action dispatcher, the secondary-subtitle mode cycle, queueing the clipboard's video, and the mpv commands the overlay renderer sends. The runtime option cycle both paths used is now one function.

* refactor(main): move Whisper subtitle generation into an assembly

* refactor(main): resolve subtitle annotation options in a runtime module

The runtime-option-over-config resolution that the texthooker page and the MeCab startup decision share moves out of main.ts into createAnnotationOptions.

* test(main): cover a non-boolean runtime annotation option value

* docs: describe the plugins, session actions and subtitle generation assemblies

Update ownership for overlay geometry and pointer interaction, the autoplay-ready gate, and annotation options; point the overlay priming entry points at their new modules; the main-wiring regex debt is gone.

* build: export MpvClientEvents so declaration emit can name the plugins assembly's return type

docs-site/architecture.md

@@ -24,7 +24,7 @@ src/
   preload*.ts             # preload bridges (overlay, settings, stats, sync, Jellyfin setup)
   main/                   # main-process runtime modules and IPC/CLI wiring
     boot/                 # pre-ready boot helpers
-    assemblies/           # per-domain assemblies main.ts builds once (startup, overlay, playback, mining, stats, Yomitan, shortcuts, tray, first-run setup, YouTube, Jellyfin, AniList, settings, sync, dictionaries, overlay modals)
+    assemblies/           # per-domain assemblies main.ts builds once (startup, overlay, playback, mining, stats, Yomitan, shortcuts, session actions, plugins, subtitle generation, tray, first-run setup, YouTube, Jellyfin, AniList, settings, sync, dictionaries, overlay modals)
     runtime/composers/    # larger runtime clusters assembled for main.ts
     runtime/domains/      # domain barrels (startup, overlay, mpv, ipc, shortcuts, anilist, jellyfin, mining)
   core/services/          # focused services: mpv client, overlay, tokenizer, mining, integrations, stats
@@ -139,7 +139,7 @@ Runtime code uses dependency injection:
 2. Build its runtime dependencies in a `src/main/` module. Pass simple dependencies inline; extract an adapter only when it adds behavior or gets reused.
 3. Call the service from lifecycle or command wiring.
 
-Domain handlers live in the barrels under `src/main/runtime/domains/`. Larger clusters, such as app-ready startup, mpv, Jellyfin, AniList tracking, shortcuts, and IPC, are assembled by composers in `src/main/runtime/composers/`. A domain whose runtimes share state, such as app startup, the overlay windows, mpv playback and subtitle state, card mining, stats, YouTube, Jellyfin, AniList, config settings, sync, or the character dictionary, is grouped into one assembly in `src/main/assemblies/` that owns that state and returns its runtimes. An assembly that answers renderer IPC or CLI commands also returns typed `ipc`/`cli` slices, and `main.ts` registers the handlers by combining those slices. Handlers take their dependencies as a plain object passed straight to the handler factory, which keeps side effects out of the unit under test.
+Domain handlers live in the barrels under `src/main/runtime/domains/`. Larger clusters, such as app-ready startup, mpv, Jellyfin, AniList tracking, shortcuts, and IPC, are assembled by composers in `src/main/runtime/composers/`. A domain whose runtimes share state, such as app startup, the overlay windows, mpv playback and subtitle state, card mining, stats, plugins, YouTube, Jellyfin, AniList, config settings, sync, or the character dictionary, is grouped into one assembly in `src/main/assemblies/` that owns that state and returns its runtimes. An assembly that answers renderer IPC or CLI commands also returns typed `ipc`/`cli` slices, and `main.ts` registers the handlers by combining those slices. Handlers take their dependencies as a plain object passed straight to the handler factory, which keeps side effects out of the unit under test.
 
 Composers declare their inputs with `ComposerInputs<T>` and results with `ComposerOutputs<T>` from `src/main/runtime/composers/contracts.ts`. A missing dependency then fails at compile time.