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/ADVERSARIAL_BUG_REPORT.md

@@ -0,0 +1,13 @@
+# Adversarial Bug Report: fix-stale-task-mtime-proxy
+
+## Attack Vectors Tested
+1. **Manual .state.lastedit manipulation**: A user could `touch .state.lastedit` to reset the timer — this is equivalent to `--touch` and is acceptable behavior
+2. **Deleted .state.lastedit**: `_get_edit_timestamp()` falls back to `.state` mtime — correct
+3. **Multiple tasks in implement phase**: `_touch_lastedit` called only for `primary` task (the first in-scope task) — acceptable, as the primary task is the one being edited
+4. **Clock skew**: Uses `time.time()` consistently — not a concern on local system
+5. **Stale task in single-task path**: Now correctly checked (was missing before this fix)
+
+## Findings
+No bugs found.
+
+## Verdict: PASS