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/additive-extension-model/BUG_REPORT.md

@@ -0,0 +1,21 @@
+# Bug Report: Additive Extension Model
+
+## Methodology
+Reviewed all modified files against SPEC requirements.
+
+## Acceptance Criteria
+| # | Criterion | Result |
+|---|-----------|--------|
+| 1 | orchestrate.md reads from global first | ✅ |
+| 2 | orchestrate.md checks extensions/ | ✅ |
+| 3 | onboarding.md no diff/merge upgrade | ✅ |
+| 4 | onboarding.md creates minimal files | ✅ |
+| 5 | onboarding.md documents extensions/ | ✅ |
+| 6 | update.sh does simple git pull | ✅ |
+| 7 | README.md describes new model | ✅ |
+| 8 | No regression in prompt/contract/script behavior | ✅ |
+
+## Findings
+1. **Minor**: `references/extensions.md` noted in SPEC but not created — no functional impact, documented elsewhere.
+
+## Verdict: PASS