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/SPEC.md

@@ -0,0 +1,16 @@
+# Spec: fix-dashboard-read-state
+
+## Problem
+`automaton/dashboard/core/task.py:462` (`determine_task_state`) infers task phase purely from artifact files, never reading the `.state` file. This contradicts `prompts/workflow.md` which declares `.state` as the "single source of truth." The dashboard cannot reflect the actual enforced state.
+
+## Fix
+Read the `.state` file first in `determine_task_state()`. If `.state` exists, parse the phase and map it to a `TaskState`. Fall back to artifact heuristics only if `.state` doesn't exist (pre-v2.0 tasks).
+
+The phase string in `.state` may include substates like `research:awaiting_approval` — map these to their base phase (`research`).
+
+## Acceptance Criteria
+- A task in `implement` phase (per `.state`) shows as `IMPLEMENT` in the dashboard even without IMPLEMENTATION.md
+- A task in `test_design` phase shows as `TEST_DESIGN`, not `IMPLEMENT`
+- A task without `.state` still uses artifact heuristics (backward compat)
+- Existing dashboard tests in `test_task.py` still pass
+- Add test verifying `.state` takes precedence over artifacts