Add Rules & Expectations feature with TV overlay and dashboard layout updates

- Add Rules & Expectations admin section with drag-to-reorder, add/edit/delete
- Add Overlays card to Dashboard with Rules/Expectations toggle button (LIVE badge when active)
- Add full-screen rules overlay on TV view (green theme, numbered list, tap to dismiss)
- Backend: new RuleItem model, /api/rules CRUD + bulk reorder, /api/overlays WS broadcast endpoints
- Schedule store handles show_rules / hide_rules WebSocket events
- Rearrange Dashboard top row: TV Dashboard | 3 Strikes | Overlays (3-col, mobile stacks)
- Put Today's Session and Today's Schedule side-by-side at 50/50 width (mobile stacks)
- Update README with all new features, setup steps, WS events, and project structure

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/models/__init__.py

@@ -9,6 +9,7 @@ from app.models.activity import ActivityLog
 from app.models.morning_routine import MorningRoutineItem
 from app.models.break_activity import BreakActivityItem
 from app.models.strike import StrikeEvent
+from app.models.rule import RuleItem
 
 __all__ = [
     "Base",
@@ -26,4 +27,5 @@ __all__ = [
     "MorningRoutineItem",
     "BreakActivityItem",
     "StrikeEvent",
+    "RuleItem",
 ]