Archive completed tasks, add cleanup commands, self-documenting dashboard UI

- Archive 79 completed framework-dev tasks from tasks/ -> tasks/complete/
- status.py: add --cleanup-done and --install-cleanup-schedule commands
- Add scripts/automaton-cleanup.sh for periodic task archiving
- Dashboard: rename 'Background' tab -> 'Agent', 'Cleanup' agent -> 'Completed Task Archiver', remove redundant group headers and pill badges, dim inactive agent placeholders
- .rules.md: add Self-Documenting UI Names rule
- New tests: test_cleanup_done.py, expanded test_app.py and test_task.py

tasks/complete/fix-stale-task-mtime-proxy/ADVERSARIAL_BUG_REPORT.md

@@ -0,0 +1,13 @@
+# Adversarial Bug Report: fix-stale-task-mtime-proxy
+
+## Attack Vectors Tested
+1. **Manual .state.lastedit manipulation**: A user could `touch .state.lastedit` to reset the timer — this is equivalent to `--touch` and is acceptable behavior
+2. **Deleted .state.lastedit**: `_get_edit_timestamp()` falls back to `.state` mtime — correct
+3. **Multiple tasks in implement phase**: `_touch_lastedit` called only for `primary` task (the first in-scope task) — acceptable, as the primary task is the one being edited
+4. **Clock skew**: Uses `time.time()` consistently — not a concern on local system
+5. **Stale task in single-task path**: Now correctly checked (was missing before this fix)
+
+## Findings
+No bugs found.
+
+## Verdict: PASS