Add demo tenant reseed, staff roles, and fix masquerade redirect

Demo Tenant:
- Add block_emails field to Tenant model for demo accounts
- Add is_email_blocked() and wrapper functions in email_service
- Create reseed_demo management command with salon/spa theme
- Add Celery beat task for daily reseed at midnight UTC
- Create 100 appointments, 20 customers, 13 services, 12 resources

Staff Roles:
- Add StaffRole model with permission toggles
- Create default roles: Full Access, Front Desk, Limited Staff
- Add StaffRolesSettings page and hooks
- Integrate role assignment in Staff management

Bug Fixes:
- Fix masquerade redirect using wrong role names (tenant_owner vs owner)

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

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

frontend/src/hooks/useInvitations.ts

@@ -19,6 +19,8 @@ export interface StaffInvitation {
   create_bookable_resource: boolean;
   resource_name: string;
   permissions: Record<string, boolean>;
+  staff_role_id: number | null;
+  staff_role_name: string | null;
 }
 
 export interface InvitationDetails {
@@ -52,6 +54,7 @@ export interface CreateInvitationData {
   create_bookable_resource?: boolean;
   resource_name?: string;
   permissions?: StaffPermissions;
+  staff_role_id?: number | null;
 }
 
 /**