docs: refresh roadmap current state

[mattpartida]

Summary

• Remove stale roadmap references to already-merged PRs feat: add markdown config risk summaries #2 and test: add prompt injection fixture corpus #3 as active roadmap blockers.
• Add Phase 13 healthcheck helper output gates to the roadmap current baseline.
• Add a regression test that keeps the roadmap current-state section synchronized with merged phase work.

Test Plan

• python -m pytest tests/test_phase13_healthcheck_outputs.py::test_roadmap_current_state_matches_merged_phase_work -q
• python -m compileall -q skills tests
• python -m pytest -q
• ruff check .
• ./package-skills.sh
• git diff --check