Fix 11 automation gaps: dead-end phases, autopilot runtime, guard plugin, status.py bugs, Category 3 audit

- Fix decomposition:approved and human_intervention dead-end phases
- Add scripts/autopilot.py: real drive_all() implementation
- Fix guard plugin: throw Error instead of injecting user messages
- Fix status.py: double continue, _require_state, --list-states
- Add Category 3 (git-based modification) audit
- Add Category 5 (stuck-task detection) audit
- All 206 tests pass

tasks/implement-autopilot-runtime/SPEC.md

@@ -0,0 +1,21 @@
+# Implement Autopilot Runtime
+
+## Problem
+- `drive_all()` only exists as pseudocode in orchestrate.md. No Python implementation.
+- No idle loop when all tasks complete.
+- No stuck-task detection (crash recovery, phase-stuck detection).
+
+## Fix
+Create `scripts/autopilot.py` with:
+1. `scan_all_tasks()` — reads all .state files in tasks/
+2. `is_terminal()` — checks if phase is complete or human_intervention
+3. `needs_user_input()` — checks if phase ends with :awaiting_approval or task has VERDICT.md with FAIL/NEEDS_REVIEW
+4. `drive_task()` — loads and executes the prompt for the current phase
+5. `drive_all()` — main loop that processes unblocked non-terminal tasks
+6. Idle behavior: when all tasks terminal, prompt user to create new tasks
+7. Stuck detection: tasks in same non-terminal phase > 60 min are flagged
+
+## Verification
+- `python scripts/autopilot.py --project /path/to/project` runs the autopilot
+- Handles empty queue gracefully
+- Detects and reports stuck tasks