feat(messaging): Add broadcast messaging system for owners and managers

- Add BroadcastMessage and MessageRecipient models for sending messages to groups or individuals
- Add Messages page with compose form and sent messages list
- Support targeting by role (owners, managers, staff, customers) or individual users
- Add can_send_messages permission (owners always, managers by default with revocable permission)
- Add autofill search dropdown with infinite scroll for selecting individual recipients
- Add staff permission toggle for managers' messaging access
- Integrate Messages link in sidebar for users with permission

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

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

frontend/src/api/auth.ts

@@ -47,6 +47,7 @@ export interface LoginResponse {
     business?: number;
     business_name?: string;
     business_subdomain?: string;
+    can_send_messages?: boolean;
   };
   masquerade_stack?: MasqueradeStackEntry[];
   // MFA challenge response
@@ -73,6 +74,7 @@ export interface User {
   can_invite_staff?: boolean;
   can_access_tickets?: boolean;
   can_edit_schedule?: boolean;
+  can_send_messages?: boolean;
   linked_resource_id?: number;
   quota_overages?: QuotaOverage[];
 }
@@ -134,3 +136,11 @@ export const stopMasquerade = async (
   );
   return response.data;
 };
+
+/**
+ * Request password reset email
+ */
+export const forgotPassword = async (email: string): Promise<{ message: string }> => {
+  const response = await apiClient.post<{ message: string }>('/auth/password-reset/', { email });
+  return response.data;
+};