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/CODE_REVIEW.md

@@ -0,0 +1,19 @@
+# Code Review: fix-test-plan-phase-mapping
+
+## Reviewed Files
+- `scripts/status.py` (line 348-349: `_infer_state_from_artifacts()`)
+- `automaton/dashboard/core/task.py` (line 548-549: `determine_task_state()`)
+- `tests/test_task.py`
+
+## Changes
+Changed `TEST_PLAN.md` mapping from `implement` → `test_design` in both `status.py` and dashboard `task.py`.
+
+## Analysis
+- **Correctness**: `TEST_PLAN.md` is produced during the `test_design` phase, not `implement`. The workflow is: `test_design` → (approval) → `implement`. TEST_PLAN.md is the output of `test_design`, so it should map to `test_design`.
+- **Consistency**: Both `status.py` and dashboard `task.py` now use the same mapping
+- **Test updates**: Existing tests updated to assert `TEST_DESIGN` instead of `IMPLEMENT`, and new test added for `--upgrade` inference
+- **No regression**: Tasks with both TEST_PLAN.md and IMPLEMENTATION.md still correctly map to `code_review` (because IMPLEMENTATION.md is checked first)
+
+## Verdict: PASS
+
+The fix is correct, minimal, and consistent across both enforcement and dashboard code.