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/complete/changelog/IMPLEMENTATION.md

@@ -0,0 +1,24 @@
+# Implementation: Changelog and Release Notes Process
+
+## Summary
+
+Created a root-level CHANGELOG.md and codified the changelog update process in `.rules.md`.
+
+## Changes Made
+
+### `CHANGELOG.md`
+Created at `~/.automaton/CHANGELOG.md` with:
+- `[unreleased]` header
+- `### Added` and `### Changed` sections
+- Entries for all completed tasks (additive-extension-model, framework-self-enforcement, changelog, framework-audit)
+
+### `.rules.md`
+Added "Changelog" section:
+- When a task reaches Resolution (VERDICT.md written), append an entry to CHANGELOG.md
+- Format: `- description (#task-name)` under the appropriate section
+
+## Files Created
+- `CHANGELOG.md` — root-level changelog
+
+## Files Modified
+- `.rules.md` — added changelog rules