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/remove-file-system-watcher/SPEC.md

@@ -1,20 +0,0 @@
-# SPEC: Remove File System Watcher
-
-## Goal
-Resolve the half-implemented `refresh.py` module by removing it and documenting the polling-based refresh behavior.
-
-## Requirements
-1. Delete `automaton/dashboard/core/refresh.py`.
-2. Update `automaton/dashboard/README.md` to state that auto-refresh uses client-side polling.
-3. Ensure no imports or references to `refresh.py` remain.
-
-## Acceptance Criteria
-- [ ] `automaton/dashboard/core/refresh.py` does not exist.
-- [ ] `README.md` accurately describes the polling refresh mechanism.
-- [ ] `python -m automaton.dashboard` still starts and refreshes correctly.
-
-## Non-Goals
-- Implementing Server-Sent Events or WebSocket push.
-
-## Stop Condition
-When all acceptance criteria are met, output "CONTRACT_MET".