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/fix-status-script-bugs/SPEC.md

@@ -0,0 +1,19 @@
+# Fix status.py Bugs
+
+## Problem
+1. **Neutered target-phase artifact check** (status.py:488-492): loop body is `pass`, check never executes
+2. **Double `continue`** (status.py:1003-1004, 1057-1058): unreachable dead code
+3. **`cmd_approve` uses `_read_state`** (status.py:521): weaker than `_require_state`, silently handles untracked tasks
+4. **No `--list-states` command**: agents can't discover valid phases programmatically
+
+## Fix
+1. Activate target-phase artifact check (remove `pass`, add actual validation)
+2. Remove duplicate `continue` statements
+3. Change `cmd_approve` to use `_require_state` for consistency
+4. Add `--list-states` argument that prints VALID_PHASES
+
+## Verification
+- Target-phase artifact check blocks transitions when target's required artifact is missing
+- No dead code
+- `cmd_approve` rejects untracked tasks
+- `--list-states` prints all valid phases