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-stale-task-mtime-proxy/IMPLEMENTATION.md

@@ -0,0 +1,26 @@
+# Implementation: fix-stale-task-mtime-proxy
+
+## Bug
+`--can-edit` used `.state` file mtime as a proxy for "last edit activity" to detect stale tasks. But `.state` is modified by phase transitions, not by actual editing. A task in `implement` phase for 30+ minutes would be flagged as stale even if the developer was actively editing files the whole time, because `.state` mtime only reflects the last phase transition.
+
+## Fix
+1. Added `_get_edit_timestamp()` — reads `.state.lastedit` mtime if it exists, falls back to `.state` mtime for backward compatibility
+2. Added `_touch_lastedit()` — creates/updates `.state.lastedit` file
+3. `--can-edit` now calls `_touch_lastedit()` on ALLOWED responses (both project-level and task-level paths), recording actual edit activity
+4. Staleness check uses `_get_edit_timestamp()` instead of raw `.state` mtime
+5. Added `.state.lastedit` to `NON_ARTIFACT_FILES` so it's not treated as a phase artifact
+6. `--same-session` uses `_get_edit_timestamp()` for consistent activity tracking
+7. `--touch` command now touches `.state.lastedit` instead of `.state`
+8. Added staleness check to the single-task `--can-edit --task` path (previously only project-level `--can-edit` checked staleness)
+
+## Files Changed
+- `scripts/status.py`: Added `_get_edit_timestamp()`, `_touch_lastedit()`, updated `cmd_can_edit()`, `cmd_same_session()`, `cmd_touch()`, `NON_ARTIFACT_FILES`
+- `tests/test_status.py`: Added `TestStateLastEdit` class with 5 tests and `TestTestPlanPhaseMapping` class
+
+## Tests
+- `test_can_edit_creates_lastedit_on_allowed`: Verifies `.state.lastedit` is created on ALLOWED
+- `test_can_edit_creates_lastedit_with_file_scope`: Same for file-scoped can-edit
+- `test_stale_uses_lastedit_not_state_mtime`: Old `.state` + recent `.state.lastedit` → not stale
+- `test_stale_when_lastedit_old`: Recent `.state` + old `.state.lastedit` → stale
+- `test_falls_back_to_state_mtime_without_lastedit`: No `.state.lastedit` → falls back to `.state` mtime
+- All 249 tests pass