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.

tests/test_task.py

@@ -55,7 +55,7 @@ def test_implementation_from_test_plan(tmp_path: Path) -> None:
         {"SPEC.md": "# Spec", "TEST_PLAN.md": "# Tests"},
     )
     state, _ = determine_task_state(task_dir)
-    assert state == TaskState.IMPLEMENT
+    assert state == TaskState.TEST_DESIGN
 
 
 def test_bug_find_state(tmp_path: Path) -> None:
@@ -232,10 +232,10 @@ class TestStateMachineAlignment:
         state, _ = determine_task_state(task_dir)
         assert state == TaskState.RESEARCH
 
-    def test_test_plan_shows_implement(self, tmp_path: Path) -> None:
+    def test_test_plan_shows_test_design(self, tmp_path: Path) -> None:
         task_dir = _make_task(tmp_path, "testplan", {"SPEC.md": "# Spec", "TEST_PLAN.md": "# Tests"})
         state, _ = determine_task_state(task_dir)
-        assert state == TaskState.IMPLEMENT
+        assert state == TaskState.TEST_DESIGN
 
     def test_design_with_spec_shows_design(self, tmp_path: Path) -> None:
         task_dir = _make_task(tmp_path, "design-spec", {"SPEC.md": "# Spec", "DESIGN.md": "# Design"})