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/pre-existing-fixes/BUG_REPORT.md

@@ -0,0 +1,11 @@
+# Bug Report: Pre-existing Fixes
+
+## Bugs Found: 0
+
+All fixes verified:
+1. `_infer_state_from_artifacts`: `spec_only → research` confirmed by test
+2. `_infer_state_from_artifacts`: `implementation_only → bug_find` confirmed by test
+3. `cmd_validate_folder`: empty `.state` → error, confirmed by test
+4. `cmd_validate_folder`: whitespace `.state` → error, confirmed by test
+5. `upgrade.sh`: `|| true` removed, python3 check added, git-dir detection fixed
+6. All 206 tests pass