## Implementation
- [x] Add behavior tests for listing scoped past project meeting summaries with pagination.
- [x] Add behavior tests for rejecting out-of-scope project filters.
- [x] Add behavior tests for reading scoped past summary files with line ranges.
- [x] Add behavior tests for searching project files and scoped past summaries together.
- [x] Implement read-only past project meeting summary tools.
- [x] Extend generic search to include past project summaries.
- [x] Register the new tools and update summary-agent instructions/docs.
- [x] Run focused tests.
- [x] Validate OpenSpec change.