Adds step 10.5 to gsd-new-milestone that scans pending todos against the
approved roadmap and tags matches with `resolves_phase: N` in their YAML
frontmatter. Adds a `close_phase_todos` step to execute-phase that moves
tagged todos to `completed/` when the phase completes — closing the loop
automatically with no manual cleanup.
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
