feat: Implement alert creation service with FCM notifications

- Add AlertCreationService to handle alert creation and notifications.
- Implement idempotency key support to prevent duplicate alerts.
- Create alert notification service for sending FCM messages.
- Add tests for alert creation and notification services.
- Document FCM notification flow and alert creation process.

frontend/src/pages/AlertsPage.jsx

@@ -66,12 +66,12 @@ export default function AlertsPage() {
     }
   };
 
-  const handleFormSubmit = async (data) => {
+  const handleFormSubmit = async (data, idempotencyKey) => {
     try {
       if (editingAlert) {
         await alertsApi.update(editingAlert.id, data);
       } else {
-        await alertsApi.create(data);
+        await alertsApi.create(data, idempotencyKey);
       }
       setShowForm(false);
       loadData();
@@ -390,7 +390,17 @@ function AlertCard({ alert, index, onEdit, onDelete }) {
   );
 }
 
+function createAlertIdempotencyKey() {
+  if (globalThis.crypto?.randomUUID) {
+    return globalThis.crypto.randomUUID();
+  }
+
+  return `alert-${Date.now()}-${Math.random().toString(36).slice(2)}`;
+}
+
 function AlertForm({ alert, routes, onSubmit, onCancel }) {
+  const [idempotencyKey] = useState(createAlertIdempotencyKey);
+  const [submitting, setSubmitting] = useState(false);
   const [formData, setFormData] = useState({
     route_id: alert?.route_id || '',
     alert_type: alert?.alert_type || 'info',
@@ -401,7 +411,7 @@ function AlertForm({ alert, routes, onSubmit, onCancel }) {
     is_active: alert?.is_active !== false
   });
 
-  const handleSubmit = (e) => {
+  const handleSubmit = async (e) => {
     e.preventDefault();
 
     const data = {
@@ -410,7 +420,12 @@ function AlertForm({ alert, routes, onSubmit, onCancel }) {
       end_time: formData.end_time || null
     };
 
-    onSubmit(data);
+    setSubmitting(true);
+    try {
+      await onSubmit(data, alert ? null : idempotencyKey);
+    } finally {
+      setSubmitting(false);
+    }
   };
 
   const handleChange = (e) => {
@@ -546,15 +561,24 @@ function AlertForm({ alert, routes, onSubmit, onCancel }) {
           </div>
 
           <div className="p-4 sm:p-6 border-t border-gray-200 flex flex-col-reverse sm:flex-row sm:justify-end gap-2 sm:gap-3 safe-bottom">
-            <button type="button" onClick={onCancel} className="btn-secondary w-full sm:w-auto">
+            <button
+              type="button"
+              onClick={onCancel}
+              className="btn-secondary w-full sm:w-auto"
+              disabled={submitting}
+            >
               Отмена
             </button>
-            <button type="submit" className="btn-primary w-full sm:w-auto">
-              Сохранить
+            <button
+              type="submit"
+              className="btn-primary w-full sm:w-auto"
+              disabled={submitting}
+            >
+              {submitting ? 'Сохранение…' : 'Сохранить'}
             </button>
           </div>
         </form>
       </div>
     </div>
   );
-}
+}

frontend/src/services/api.js

@@ -155,7 +155,9 @@ export const alertsApi = {
   getAll: (params) => api.get('/alerts', { params }),
   getActive: (routeId) => api.get('/alerts/active', { params: { route_id: routeId } }),
   getById: (id) => api.get(`/alerts/${id}`),
-  create: (data) => api.post('/alerts', data),
+  create: (data, idempotencyKey) => api.post('/alerts', data, {
+    headers: idempotencyKey ? { 'Idempotency-Key': idempotencyKey } : undefined
+  }),
   update: (id, data) => api.put(`/alerts/${id}`, data),
   delete: (id) => api.delete(`/alerts/${id}`),
   cleanup: () => api.post('/alerts/cleanup')