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

stats/src/hooks/useVocabulary.ts

@@ -1,4 +1,4 @@
-import { useState, useEffect } from 'react';
+import { useState, useEffect, useCallback } from 'react';
 import { getStatsClient } from './useStatsApi';
 import type { VocabularyEntry, KanjiEntry } from '../types/stats';
 
@@ -8,6 +8,9 @@ export function useVocabulary() {
   const [knownWords, setKnownWords] = useState<Set<string>>(new Set());
   const [loading, setLoading] = useState(true);
   const [error, setError] = useState<string | null>(null);
+  // Bumped by `reload` after maintenance rewrites the vocabulary tables.
+  const [reloadToken, setReloadToken] = useState(0);
+  const reload = useCallback(() => setReloadToken((token) => token + 1), []);
 
   useEffect(() => {
     let cancelled = false;
@@ -46,7 +49,7 @@ export function useVocabulary() {
     return () => {
       cancelled = true;
     };
-  }, []);
+  }, [reloadToken]);
 
-  return { words, kanji, knownWords, loading, error };
+  return { words, kanji, knownWords, loading, error, reload };
 }