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/IMPLEMENTATION.md

@@ -0,0 +1,18 @@
+# Implementation: fix-dashboard-cors-origin
+
+## Bug
+Dashboard's `app.py` set `Access-Control-Allow-Origin: *` (wildcard CORS) on all responses via `CORS_HEADERS`. Since the dashboard is a local single-origin app, this wildcard CORS header is unnecessary and poses a security risk — any malicious webpage on the machine could make requests to the dashboard API.
+
+## Fix
+1. Removed `CORS_HEADERS` dictionary (which contained `Access-Control-Allow-Origin: *` and `Access-Control-Allow-Methods`)
+2. Added `SECURITY_HEADERS` with `X-Content-Type-Options: nosniff` and `X-Frame-Options: DENY`
+3. Updated `_send_json()`, `_send_error()`, and `do_OPTIONS()` to use `SECURITY_HEADERS` instead of `CORS_HEADERS`
+4. `do_OPTIONS()` no longer returns `Access-Control-Allow-*` headers — it simply returns 204 No Content
+
+## Files Changed
+- `automaton/dashboard/ui/app.py`: Replaced `CORS_HEADERS` with `SECURITY_HEADERS`, updated all response methods
+- `tests/test_app.py`: Updated CORS-related tests to assert NO `Access-Control-Allow-Origin` header is present, and that security headers are sent
+
+## Tests
+- `test_app.py` tests updated to verify security headers (`X-Content-Type-Options`, `X-Frame-Options`) and absence of CORS headers
+- All 249 tests pass