feat: rich AST extraction with classes, methods, calls, and raises

- Upgrade tree-sitter to 0.22.4 with compatible grammar versions
- Add Python support via tree-sitter-python@0.23.6
- Add Go support via tree-sitter-go@0.23.4
- Extract class hierarchies with method signatures (params, returns)
- Extract call graphs including external library calls
- Extract exception raises (ValueError, Error, etc)
- Extract top-level functions with full signatures
- Encode rich AST data into compact markdown format:
  class:Name, method:name(params)→return, call:..., raise:...
- Deduplicate nested call chains (db.query vs db.query().where())
- Filter out simple export names when rich func/class entries exist
- All 55 tests passing

package.json

@@ -45,7 +45,9 @@
     "openai": "^6.42.0",
     "p-limit": "^7.3.0",
     "picocolors": "^1.1.1",
-    "tree-sitter": "^0.21.0",
-    "tree-sitter-typescript": "^0.21.0"
+    "tree-sitter": "^0.22.4",
+    "tree-sitter-go": "^0.23.4",
+    "tree-sitter-python": "^0.23.6",
+    "tree-sitter-typescript": "^0.23.2"
   }
 }