feat: Add time block approval workflow and staff permission system

- Add TimeBlock approval status with manager approval workflow
- Create core mixins for staff permission restrictions (DenyStaffWritePermission, etc.)
- Add StaffDashboard page for staff-specific views
- Refactor MyAvailability page for time block management
- Update field mobile status machine and views
- Add per-user permission overrides via JSONField
- Document core mixins and permission system in CLAUDE.md

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/App.tsx

@@ -35,6 +35,7 @@ const TermsOfServicePage = React.lazy(() => import('./pages/marketing/TermsOfSer
 
 // Import pages
 const Dashboard = React.lazy(() => import('./pages/Dashboard'));
+const StaffDashboard = React.lazy(() => import('./pages/StaffDashboard'));
 const StaffSchedule = React.lazy(() => import('./pages/StaffSchedule'));
 const Scheduler = React.lazy(() => import('./pages/Scheduler'));
 const Customers = React.lazy(() => import('./pages/Customers'));
@@ -667,7 +668,7 @@ const AppContent: React.FC = () => {
             {/* Regular Routes */}
             <Route
               path="/"
-              element={user.role === 'resource' ? <ResourceDashboard /> : <Dashboard />}
+              element={user.role === 'resource' ? <ResourceDashboard /> : user.role === 'staff' ? <StaffDashboard user={user} /> : <Dashboard />}
             />
             {/* Staff Schedule - vertical timeline view */}
             <Route