fix(stats): stop counting duplicate typeset subtitle lines

- Collapse animation-burst subtitle lines (karaoke OPs, animated signs) at ingest time using the same dedup rules the subtitle sidebar already applies, so repeated frames no longer flood "Top Repeated Words"
- Add retroactive cleanup for stats already affected: a "Duplicates" scanner/cleaner in the Vocabulary tab and `subminer stats cleanup --duplicate-lines` (`--dry-run`, `--lookback-days`) on the CLI
- Only subtitle lines and the vocabulary counts they feed are touched; watch time and lines-seen totals are left as recorded

src/core/services/subtitle-cue-dedup.ts

@@ -7,31 +7,20 @@
  */
 
 import { hasAssTemporalOverride, isAnimatedAssEffectKind } from './ass-text';
+import {
+  ANIMATION_FRAME_MAX_SECONDS,
+  DUPLICATE_CUE_GAP_TOLERANCE_SECONDS,
+  MIN_BURST_EVENTS,
+  MIN_TAGGED_BURST_FRAMES,
+  MIN_TIMING_ONLY_FRAMES,
+  TIMING_ONLY_FRAME_MAX_SECONDS,
+} from './subtitle-burst-constants';
 import type {
   AnnotatedSubtitleCue,
   SubtitleCue,
   SubtitleSourceFormat,
 } from './subtitle-cue-parser';
 
-// Back-to-back frames of the same animation are authored flush against each other; a
-// tiny tolerance absorbs the centisecond rounding of the ASS timestamp format.
-const DUPLICATE_CUE_GAP_TOLERANCE_SECONDS = 0.05;
-// A burst is a *sequence*. Two adjacent events are two events, not an animation --
-// characters do repeat each other, and a repeated line can legitimately be short.
-const MIN_BURST_EVENTS = 3;
-// Real dialogue holds on screen for about a second, so a run with a couple of much
-// shorter events among them looks like frames. Used only alongside authoring evidence.
-const ANIMATION_FRAME_MAX_SECONDS = 0.3;
-// A karaoke run usually ends on a long "hold" frame, so not every event is short.
-const MIN_TAGGED_BURST_FRAMES = 2;
-// SRT and VTT carry no authoring metadata at all, so timing is the only signal available
-// -- which makes it the easiest one to get wrong. ASS->SRT conversion leaves frames at
-// ~0.04s, well under any real utterance, and a burst leaves many of them behind. Both
-// bounds are deliberately far stricter than the ASS path: a run of ordinary short lines
-// (`えっ` traded between characters) must not clear them.
-const TIMING_ONLY_FRAME_MAX_SECONDS = 0.1;
-const MIN_TIMING_ONLY_FRAMES = 5;
-
 function cueKey(cue: SubtitleCue): string {
   return `${cue.startTime}|${cue.endTime}|${cue.text}`;
 }