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/spec-in-detail/IMPLEMENTATION.md

@@ -1,17 +0,0 @@
-# Implementation: SPEC.md Content in Task Detail Panel
-
-## Summary
-
-Added SPEC.md content display in the task detail panel so reviewers can see the specification when reviewing a task.
-
-## Changes Made
-
-### Backend (`app.py`)
-- `_serve_tasks()` and `_serve_task()` now include `spec_content` field from the task's SPEC.md
-
-### Frontend (`dashboard.js`)
-- `renderDetail()` renders SPEC.md content in a "Specification" section using `<pre class="detail-content-text">`
-
-## Files Modified
-- `automaton/dashboard/ui/app.py` — added spec_content to API responses
-- `automaton/dashboard/html/dashboard.js` — renders specification section in detail panel