refactor(ipc): remove dead preload methods and the ASS line broadcast (#293)

Drop 16 overlay preload methods with no caller (onSubtitleAss,
getCurrentSubtitleAss, onVisibility, getOverlayVisibility,
openYomitanSettings, quitApp, toggleOverlay, getMecabStatus,
setMecabEnabled, getKeybindings, saveControllerPreference,
getAnkiConnectStatus, setAnkiConnectEnabled, clearAnkiConnectHistory,
cycleRuntimeOption, appendClipboardVideoToQueue) along with their
IPC_CHANNELS keys, handlers, validators and dep plumbing.

With both ASS consumers gone, stop observing sub-text/ass in mpv and
remove the subtitle-ass-change event chain and appState.currentSubAssText.
The main-process functions these wrapped stay; tray, CLI, shortcuts and
session actions still use them.

src/core/services/runtime-options-ipc.ts

@@ -34,19 +34,3 @@ export function setRuntimeOptionFromIpcRuntime(
   }
   return result;
 }
-
-export function cycleRuntimeOptionFromIpcRuntime(
-  manager: RuntimeOptionsManagerLike | null,
-  id: RuntimeOptionId,
-  direction: 1 | -1,
-  showMpvOsd: (text: string) => void,
-): RuntimeOptionApplyResult {
-  if (!manager) {
-    return { ok: false, error: 'Runtime options manager unavailable' };
-  }
-  const result = applyRuntimeOptionResultRuntime(manager.cycleOption(id, direction), showMpvOsd);
-  if (!result.ok && result.error) {
-    showMpvOsd(result.error);
-  }
-  return result;
-}