feat(anime): queue episodes to play next across anime

- Episode rows gain Play/Queue actions (and matching context-menu items); queued rows show their place in line, with a queue count and Clear queue in the episode header
- Queue lives in the main process (`anime-browser-queue.ts`) so it survives the browser window closing and advances on mpv's end-file even when nobody is watching; streams resolve at play time so a signed URL cannot expire while queued
- Holds mpv's keep-open off while the queue waits and restores it once empty; queueing with nothing playing just plays immediately
- Adds anime-browser-queue and episode-queue unit tests, IPC channels/contracts, and doc updates

src/main/runtime/anime-browser-runtime-deps.ts

@@ -11,7 +11,11 @@ import type { SubtitleCacheIo } from '../../anime-bridge/subtitle-cache';
 import type { BundleBinaries } from '../../anime-bridge/sidecar-bundle';
 import { startSidecar } from '../../anime-bridge/sidecar-process';
 import { startStreamStripProxy } from '../../anime-bridge/stream-strip-proxy';
-import type { AnimeBrowserBridgeState, AnimeBrowserSearchUpdate } from '../../types/anime-browser';
+import type {
+  AnimeBrowserBridgeState,
+  AnimeBrowserQueueState,
+  AnimeBrowserSearchUpdate,
+} from '../../types/anime-browser';
 import type { InstallProgress } from './anime-bridge-installer';
 
 export interface AnimeBrowserRuntimeDeps {
@@ -53,6 +57,8 @@ export interface AnimeBrowserRuntimeDeps {
   /** Overrides the filesystem/network the subtitle cache uses. Tests only. */
   subtitleCacheIo?: SubtitleCacheIo;
   onBridgeState: (state: AnimeBrowserBridgeState) => void;
+  /** Pushes the play queue to the browser window, advances included. */
+  onQueueState?: (state: AnimeBrowserQueueState) => void;
   /** Streams per-source progress while a search invoke is pending. */
   onSearchUpdate?: (update: AnimeBrowserSearchUpdate) => void;
   preferredQuality?: () => string | undefined;