Fix 10 audit bugs: path prefix matching, verdict parsing, CORS, stale-task detection, phase mapping

Batch 1 (High severity):
- Bug 1: --audit cat3 now checks .automaton/tasks/ paths
- Bug 4: Verdict PASS/FAIL uses structured ## Status: line parsing
- Bug 5: register-guards.sh checks .json/.jsonc, writes plugin key, strips comments
- Bug 7: --can-edit/--scope-check path prefix uses os.sep boundary

Batch 2 (Medium/Low severity):
- Bug 2: migrate-project.sh find command parentheses for -prune binding
- Bug 3: vram_detect model prefix matching with known-suffix whitelist
- Bug 6: dashboard reads .state file before artifact heuristic fallback
- Bug 8: removed wildcard CORS, added security headers (nosniff, DENY)
- Bug 9: stale-task detection uses .state.lastedit instead of .state mtime
- Bug 10: TEST_PLAN.md maps to test_design (was implement)

249 tests pass (up from 235). All 10 tasks driven through full workflow to completion.

tasks/fix-test-plan-phase-mapping/DOC_REVIEW.md

@@ -0,0 +1,12 @@
+# Doc Review: fix-test-plan-phase-mapping
+
+## Documentation Impact
+No documentation changes needed. The phase mapping fix aligns the code with the documented workflow (TEST_PLAN.md is produced during test_design phase, not implement).
+
+## Checklist
+- [x] AGENTS.md LEGAL_TRANSITIONS already show `test_design` → `implement` (TEST_PLAN.md is test_design output)
+- [x] prompts/workflow.md phase descriptions already correct
+- [x] No user-facing documentation referenced the old (buggy) mapping
+- [x] CHANGELOG.md will be updated for the release
+
+## Verdict: PASS