All 4 child beads verified closed (pdftract-1w5u1, pdftract-4q8cq, pdftract-4sky1, pdftract-653ah).
Doctor subcommand fully functional with:
- Module structure: checks/, output/ submodules
- Exit code policy: 0 for OK/WARN, 1 for FAIL
- JSON output via --json flag
- Features listing via --features flag
- Catch_unwind protection for all checks
- Runbook integration at docs/operations/manual-platform-smoke.md
- 12 unit tests passing
Closes: pdftract-2um5s
