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/ADVERSARIAL_BUG_REPORT.md

@@ -0,0 +1,12 @@
+# Adversarial Bug Report: fix-test-plan-phase-mapping
+
+## Attack Vectors Tested
+1. **Task with both TEST_PLAN.md and IMPLEMENTATION.md**: IMPLEMENTATION.md is checked first in both status.py and task.py, so it correctly maps to `code_review` — no regression
+2. **Task with TEST_PLAN.md only**: Maps to `test_design` — correct
+3. **Task with TEST_PLAN.md and CODE_REVIEW.md**: CODE_REVIEW.md checked first → `bug_find` — correct
+4. **Case sensitivity of filenames**: Artifact check uses exact string match — `test_plan.md` (lowercase) would not match `TEST_PLAN.md` — this is existing behavior, not a new issue
+
+## Findings
+No bugs found.
+
+## Verdict: PASS