feat: Improve exact name match scoring and expand stop word filtering

Uses max FTS score as baseline for exact name matches to ensure nameMatchBonus differentiation during rescoring, increases exact match limit from 5 to 20 candidates, and adds common conversational terms to stop words to reduce query noise.

src/search/query-utils.ts

@@ -20,9 +20,12 @@ export const STOP_WORDS = new Set([
   'every', 'how', 'what', 'where', 'when', 'who', 'which', 'why',
   'i', 'me', 'my', 'we', 'our', 'you', 'your', 'he', 'she', 'they',
   'show', 'give', 'tell',
-  'been', 'done', 'made', 'used', 'using', 'works', 'found',
+  'been', 'done', 'made', 'used', 'using', 'work', 'works', 'found',
   'also', 'into', 'then', 'than', 'just', 'more', 'some', 'such',
   'over', 'only', 'out', 'its', 'so', 'up', 'as', 'if',
+  'look', 'need', 'needs', 'want', 'happen', 'happens',
+  'affect', 'affected', 'break', 'breaks', 'failing',
+  'implemented', 'implement',
   // Code-specific noise (avoid filtering common symbol names like get/set/add/build/find/list)
   'code', 'file', 'files', 'function', 'method', 'class', 'type',
   'fix', 'bug', 'called',