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-read-state/IMPLEMENTATION.md

@@ -0,0 +1,15 @@
+# Implementation: fix-dashboard-read-state
+
+## Bug
+Dashboard's `determine_task_state()` in `task.py` inferred task phase from artifact filenames only, ignoring the `.state` file. This caused the dashboard to show incorrect states when the `.state` file (source of truth) disagreed with the artifact heuristic.
+
+## Fix
+1. Added `_state_string_to_task_state()` helper function that maps state machine phase strings (e.g. `"implement"`, `"code_review:awaiting_approval"`) to `TaskState` enum values. Handles sub-states by splitting on `":"` and using the base phase.
+2. Modified `determine_task_state()` to read the `.state` file first. If `.state` exists and maps to a valid `TaskState`, that takes precedence. The artifact heuristic is now a fallback for tasks without `.state` files.
+
+## Files Changed
+- `automaton/dashboard/core/task.py`: Added `_state_string_to_task_state()` function, modified `determine_task_state()` to read `.state` before falling back to artifact heuristic
+
+## Tests
+- Existing tests in `test_task.py` continue to pass (they test the artifact fallback path since test tasks don't have `.state` files by default)
+- All 249 tests pass