fix(hooks,db,mcp,worker): add type safety and error handling (#21)

- [x] Add type checking and error handling for JSON type assertions in user-prompt hook
- [x] Add error handling for session update query in CreateSDKSession
- [x] Update MCP tool description to reference sqlite-vec instead of ChromaDB
- [x] Fix MinConfidence sentinel value check from 0 to -1
- [x] Pass project parameter to vector search filter in handleSearchByPrompt
- [x] Return empty map instead of nil for successful responses without JSON body

pkg/hooks/worker.go

@@ -251,8 +251,8 @@ func POST(port int, path string, body interface{}) (map[string]interface{}, erro
 
 	var result map[string]interface{}
 	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
-		// Not all endpoints return JSON
-		return nil, nil
+		// Not all endpoints return JSON body - return empty map for success with no body
+		return map[string]interface{}{}, nil
 	}
 
 	return result, nil