The FTS5 trigram tokenizer requires >=3 CJK characters per individual
token to produce matchable trigrams. A query like "广西 OR 桂林 OR 漓江"
has cjk_count=6 (passes the existing >=3 guard) but each token is only
2 CJK chars, so the trigram index returns 0 results.
Fix:
- Add per-token check: if any non-operator CJK token has <3 CJK chars,
force the LIKE fallback path regardless of total cjk_count.
- Expand the LIKE fallback to build one LIKE condition per non-operator
token joined with OR, so each term is matched independently.
Regression tests added in TestCJKSearchFallback:
- test_cjk_or_combined_short_tokens_returns_results
- test_cjk_short_token_or_query_preserves_filters
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