feat(subtitles): add regex subtitle filters with built-in presets (#318)

- Add `subtitleFilter` config with four presets: parentheses, brackets, speaker prefix and music symbols. Custom regex rules run after the presets.
- Filter primary text where it enters the app (live `sub-text` and parsed cues), so the overlay, sidebar, mining and stats all get the same filtered text.
- Changes hot-reload: the current line is read again and the active track is parsed again, using the filter config as the prefetch parse key.
- Add a custom rule editor in Settings under Behavior → Subtitle Filters that checks patterns as you type.
- Update the config example, the configuration docs and the architecture domains doc, and add a changelog fragment.

src/core/services/mpv-protocol.ts

@@ -1,6 +1,8 @@
 import { MpvSubtitleRenderMetrics } from '../../types';
 import { sanitizeMediaTitle } from '../../shared/media-identity';
 import { widenHalfwidthKana } from '../utils/halfwidth-kana';
+import { filterSubtitleText } from '../../shared/subtitle-text-filter';
+import type { SubtitleFilterConfig } from '../../types/subtitle';
 import type { PluginMpvEventMap } from '../../plugin-api';
 import { toVideoClock } from './subtitle-clock';
 
@@ -68,6 +70,7 @@ export interface MpvProtocolParseResult {
 export interface MpvProtocolHandleMessageDeps {
   getResolvedConfig: () => {
     secondarySub?: { secondarySubLanguages?: Array<string> };
+    subtitleFilter?: SubtitleFilterConfig;
   };
   getSubtitleMetrics: () => MpvSubtitleRenderMetrics;
   isVisibleOverlayVisible: () => boolean;
@@ -263,13 +266,19 @@ export function splitMpvMessagesFromBuffer(
   };
 }
 
+// Primary text enters the app here, so every consumer sees it widened and filtered.
+function toPrimarySubText(data: unknown, deps: MpvProtocolHandleMessageDeps): string {
+  const text = widenHalfwidthKana(typeof data === 'string' ? data : '');
+  return filterSubtitleText(text, deps.getResolvedConfig().subtitleFilter);
+}
+
 export async function dispatchMpvProtocolMessage(
   msg: MpvMessage,
   deps: MpvProtocolHandleMessageDeps,
 ): Promise<void> {
   if (msg.event === 'property-change') {
     if (msg.name === 'sub-text') {
-      const nextSubText = widenHalfwidthKana((msg.data as string) || '');
+      const nextSubText = toPrimarySubText(msg.data, deps);
       const overlayVisible = deps.isVisibleOverlayVisible();
       deps.emitSubtitleChange({
         text: nextSubText,
@@ -498,7 +507,7 @@ export async function dispatchMpvProtocolMessage(
         }>,
       );
     } else if (msg.request_id === MPV_REQUEST_ID_SUBTEXT) {
-      const nextSubText = widenHalfwidthKana((msg.data as string) || '');
+      const nextSubText = toPrimarySubText(msg.data, deps);
       deps.setCurrentSubText(nextSubText);
       deps.emitSubtitleChange({
         text: nextSubText,

src/core/services/mpv.ts

@@ -3,6 +3,7 @@ import { EventEmitter } from 'events';
 import { Config, MpvClient, MpvSubtitleRenderMetrics } from '../../types';
 import {
   dispatchMpvProtocolMessage,
+  MPV_REQUEST_ID_SUBTEXT,
   MPV_REQUEST_ID_TRACK_LIST_AUDIO,
   MPV_REQUEST_ID_TRACK_LIST_SECONDARY,
   MpvMessage,
@@ -585,6 +586,11 @@ export class MpvIpcClient implements MpvClient {
     });
   }
 
+  /** Re-reads `sub-text` so the current line passes through the protocol handler again. */
+  refreshSubtitleText(): void {
+    this.send({ command: ['get_property', 'sub-text'], request_id: MPV_REQUEST_ID_SUBTEXT });
+  }
+
   async requestProperty(name: string): Promise<unknown> {
     const response = await this.request(['get_property', name]);
     if (response.error && response.error !== 'success') {