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/SPEC.md

@@ -0,0 +1,14 @@
+# Spec: fix-stale-task-mtime-proxy
+
+## Problem
+`scripts/status.py:965,1072` uses the `.state` file's mtime as a proxy for "last edit activity." But every `--transition` rewrites `.state`, resetting its mtime. A task that was transitioned 29 minutes ago appears "fresh" even though no editing happened. The `--same-session` check also gives false positives after any transition.
+
+## Fix
+Use a separate `.state.lastedit` timestamp file that is updated only when `--can-edit` returns ALLOWED (actual edit activity). Check `.state.lastedit` mtime instead of `.state` mtime for stale-task detection. If `.state.lastedit` doesn't exist, fall back to `.state` mtime (backward compat).
+
+## Acceptance Criteria
+- Transitioning a task does NOT reset the stale-task timer
+- Running `--can-edit` (and getting ALLOWED) DOES reset the timer
+- If `.state.lastedit` doesn't exist, falls back to `.state` mtime
+- Existing tests still pass
+- Add test verifying transition doesn't reset timer but can-edit does