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-can-edit-path-prefix/CODE_REVIEW.md

@@ -0,0 +1,15 @@
+# Code Review: fix-can-edit-path-prefix
+
+## Summary
+Fixes path prefix matching at 5 locations to prevent sibling-directory bypass.
+
+## Findings
+- **Correctness**: `str(file_path).startswith(proj_str + os.sep) or str(file_path) == proj_str` correctly handles both files inside the directory and the directory itself. The `os.sep` ensures the boundary is a path separator, preventing `/home/user/project-evil` from matching `/home/user/project`.
+- **Consistency**: All 5 locations use the same pattern — good.
+- **Edge cases**: 
+  - A file exactly at `proj_str` (the project root itself) is handled by the `== proj_str` clause.
+  - Symlinks: `Path.resolve()` is called on `file_path`, so symlinks are resolved before comparison. This is correct.
+- **Tests**: 3 tests cover the sibling-rejection, subdirectory-acceptance, and can-edit-task scenarios.
+
+## Verdict
+APPROVED — no issues found.