Generates the "what's new" release summary and diff file for changes in the Flutter engine (//engine/src/flutter) between two releases (e.g., 3.47 vs 3.44). When to use: - Only activate when explicitly asked by the user to generate what's new in the engine, diff Flutter engine releases, or produce an engine release summary. When not to use: - Do not use for general questions about commits, individual file history, or codebase searches unless explicitly requested to generate the engine release diff or summary.