Ingest MCAP driving logs and query them by timestamp

Build a small data service over recorded vehicle drives, with an AI coding assistant allowed. Each drive (a run) is stored as an MCAP file: timestamped messages on several topics, such as camera, lidar and vehicle state.

1. Write the ingestion step: read a run's MCAP file and store its messages so they can be looked up by run, topic and time.
2. Expose a query API that, given a run and a timestamp (or a time range), returns the messages recorded at or near that time.

Be ready to explain your storage layout, how lookups stay fast for long runs, and what you would change for many large runs.