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/readme-upgrade-docs/BUG_REPORT.md

@@ -1,10 +0,0 @@
-# Bug Report: README and Upgrade Docs
-
-## Bugs Found: 0
-
-No bugs found. Changes are documentation-only and all tests pass.
-
-## Issues Noted (pre-existing, not introduced by this task)
-1. `upgrade.sh` uses `|| true` so `status.py --upgrade` failure is silently swallowed
-2. `upgrade.sh` doesn't verify python3 is available
-3. Pre-commit hook assumes `.git/hooks/` path (doesn't handle bare repos/worktrees)