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/fix-dashboard-read-state/IMPLEMENTATION.md

@@ -0,0 +1,15 @@
+# Implementation: fix-dashboard-read-state
+
+## Bug
+Dashboard's `determine_task_state()` in `task.py` inferred task phase from artifact filenames only, ignoring the `.state` file. This caused the dashboard to show incorrect states when the `.state` file (source of truth) disagreed with the artifact heuristic.
+
+## Fix
+1. Added `_state_string_to_task_state()` helper function that maps state machine phase strings (e.g. `"implement"`, `"code_review:awaiting_approval"`) to `TaskState` enum values. Handles sub-states by splitting on `":"` and using the base phase.
+2. Modified `determine_task_state()` to read the `.state` file first. If `.state` exists and maps to a valid `TaskState`, that takes precedence. The artifact heuristic is now a fallback for tasks without `.state` files.
+
+## Files Changed
+- `automaton/dashboard/core/task.py`: Added `_state_string_to_task_state()` function, modified `determine_task_state()` to read `.state` before falling back to artifact heuristic
+
+## Tests
+- Existing tests in `test_task.py` continue to pass (they test the artifact fallback path since test tasks don't have `.state` files by default)
+- All 249 tests pass