feat: Extract type references from annotations and improve symbol query matching

Adds type annotation parsing to create references edges for parameter types, return types, and variable type annotations in TypeScript and other typed languages. Expands symbol extraction from queries to capture lowercase identifiers and filters out more common English words. Removes obsolete search utility tests.

src/context/index.ts

@@ -83,13 +83,30 @@ function extractSymbolsFromQuery(query: string): string[] {
     }
   }
 
-  // Filter out common English words that might match patterns
+  // Extract plain lowercase identifiers (3+ chars, not already matched)
+  // Catches symbol names like "undo", "redo", "history", "render", "parse"
+  const lowercasePattern = /\b([a-z][a-z0-9]{2,})\b/g;
+  while ((match = lowercasePattern.exec(query)) !== null) {
+    if (match[1]) {
+      symbols.add(match[1]);
+    }
+  }
+
+  // Filter out common English words that aren't likely symbol names
   const commonWords = new Set([
     'the', 'and', 'for', 'with', 'from', 'this', 'that', 'have', 'been',
     'will', 'would', 'could', 'should', 'does', 'done', 'make', 'made',
     'use', 'used', 'using', 'work', 'works', 'find', 'found', 'show',
     'call', 'called', 'calling', 'get', 'set', 'add', 'all', 'any',
-    'how', 'what', 'when', 'where', 'which', 'who', 'why'
+    'how', 'what', 'when', 'where', 'which', 'who', 'why',
+    'not', 'but', 'are', 'was', 'were', 'has', 'had', 'its',
+    'can', 'did', 'may', 'also', 'into', 'than', 'then', 'them',
+    'each', 'other', 'some', 'such', 'only', 'same', 'about',
+    'after', 'before', 'between', 'through', 'during', 'without',
+    'again', 'further', 'once', 'here', 'there', 'both', 'just',
+    'more', 'most', 'very', 'being', 'having', 'doing',
+    'system', 'need', 'needs', 'want', 'wants', 'like', 'look',
+    'change', 'changes', 'changed', 'changing',
   ]);
 
   return Array.from(symbols).filter(s => !commonWords.has(s.toLowerCase()));