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/config/definitions/defaults-subtitle.ts

@@ -1,6 +1,9 @@
 import { ResolvedConfig } from '../../types/config';
 
-export const SUBTITLE_DEFAULT_CONFIG: Pick<ResolvedConfig, 'subtitleStyle' | 'subtitleSidebar'> = {
+export const SUBTITLE_DEFAULT_CONFIG: Pick<
+  ResolvedConfig,
+  'subtitleStyle' | 'subtitleSidebar' | 'subtitleFilter'
+> = {
   subtitleStyle: {
     primaryDefaultMode: 'visible',
     css: {},
@@ -94,4 +97,13 @@ export const SUBTITLE_DEFAULT_CONFIG: Pick<ResolvedConfig, 'subtitleStyle' | 'su
     activeLineBackgroundColor: 'rgba(138, 173, 244, 0.22)',
     hoverLineBackgroundColor: 'rgba(54, 58, 79, 0.84)',
   },
+  subtitleFilter: {
+    presets: {
+      parentheses: false,
+      brackets: false,
+      speakerPrefix: false,
+      musicSymbols: false,
+    },
+    customRules: [],
+  },
 };