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/port-pi-guard/IMPLEMENTATION.md

@@ -1,18 +0,0 @@
-# Port Guard to Pi Dev Implementation
-
-## Summary
-Created pi dev extension at `plugins/automaton-guard-pi/` using the `@earendil-works/pi-coding-agent` API.
-
-## Changes
-
-### New Files
-- `plugins/automaton-guard-pi/guard.ts` — Pre-edit guard for pi dev harness
-  - Intercepts `tool_call` events for edit/write/bash tools
-  - Calls `status.py --can-edit` before allowing file modifications
-  - Handles stale task detection with user notification
-  - Uses `child_process.execSync` for status.py invocation
-- `plugins/automaton-guard-pi/package.json` — Package manifest with pi-coding-agent peer dependency
-
-### Integration
-- `scripts/register-guards.sh` — Detects `pi` in PATH and installs the guard via `pi install`
-- `contracts/harness-integration.md` — Updated enforcement matrix to include Pi Dev