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-dead-end-phases/SPEC.md

@@ -1,13 +0,0 @@
-# Fix Dead-End Phases
-
-## Problem
-- `decomposition:approved` has `[]` in LEGAL_TRANSITIONS (status.py:91). Parent tasks stuck forever.
-- `human_intervention` not in LEGAL_TRANSITIONS at all. Referee can transition into it but never out.
-
-## Fix
-1. Add `decomposition:approved → [complete]` to LEGAL_TRANSITIONS (parent task completes when all subtasks done)
-2. Add `human_intervention → [referee, complete]` to LEGAL_TRANSITIONS (user can send back to referee or mark complete)
-
-## Verification
-- `status.py --transition complete --task <t> --project .` on a decomposition:approved task should succeed
-- `status.py --transition referee --task <t> --project .` on a human_intervention task should succeed