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-dashboard-cors-origin/SPEC.md

@@ -0,0 +1,17 @@
+# Spec: fix-dashboard-cors-origin
+
+## Problem
+`automaton/dashboard/ui/app.py:40-44` sets `Access-Control-Allow-Origin: *` on all responses, including POST and PUT endpoints. Any website open in the user's browser can send cross-origin requests to `localhost:8080`, allowing silent modification of task reviews and config.
+
+## Fix
+Remove the wildcard CORS origin. The dashboard is a local single-origin app — CORS headers are unnecessary. Either:
+1. Remove `CORS_HEADERS` entirely and stop sending them, OR
+2. Set `Access-Control-Allow-Origin` to `http://localhost:{port}` only
+
+Option 1 is simpler and safer. The dashboard serves both the HTML and the API from the same origin, so CORS is not needed.
+
+## Acceptance Criteria
+- No `Access-Control-Allow-Origin: *` header in responses
+- Cross-origin requests from other websites are blocked by the browser
+- Same-origin dashboard HTML can still fetch the API (no CORS needed)
+- Existing CORS tests in `test_app.py` updated to reflect the change