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/fix-stale-task-mtime-proxy/VERDICT.md

@@ -1,13 +0,0 @@
-# Verdict: fix-stale-task-mtime-proxy
-
-## Status: PASS
-
-## Summary
-Fixed stale-task detection to use `.state.lastedit` timestamp (touched on actual edit activity via `--can-edit` ALLOWED) instead of `.state` mtime (which only reflects phase transitions). Added backward-compatible fallback to `.state` mtime. Added staleness check to single-task `--can-edit --task` path. Updated `--touch` and `--same-session` for consistency. 5 new tests added.
-
-## Artifacts
-- IMPLEMENTATION.md: Complete
-- CODE_REVIEW.md: PASS
-- BUG_REPORT.md: No bugs found
-- ADVERSARIAL_BUG_REPORT.md: No bugs found
-- DOC_REVIEW.md: PASS