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/implement-task/BUG_REPORT.md

@@ -1,8 +0,0 @@
-# Bug Report: Dashboard Implementation
-
-## Findings
-
-### Finding 1: Minor
-- **Issue**: Filter bar doesn't update column headers immediately when filtered
-- **Impact**: Low - columns still show all tasks
-- **Fix**: Re-render board after filter changes