fix: tag color bug, FormData interceptor, falsy id check

- Fix tag using category_color instead of its own color when editing
- Add FormData auto-detection interceptor in client.ts (root cause of 422)
- Remove redundant Content-Type overrides from all 5 upload endpoints
- Fix falsy id check (id: 0 treated as null) with strict comparison
- Await invalidateQueries to prevent stale dropdown data

src/api/adminBroadcasts.ts

@@ -242,11 +242,7 @@ export const adminBroadcastsApi = {
     formData.append('file', file);
     formData.append('media_type', mediaType);
 
-    const response = await apiClient.post<MediaUploadResponse>('/cabinet/media/upload', formData, {
-      headers: {
-        'Content-Type': 'multipart/form-data',
-      },
-    });
+    const response = await apiClient.post<MediaUploadResponse>('/cabinet/media/upload', formData);
     return response.data;
   },
 };

src/api/adminPinnedMessages.ts

@@ -163,11 +163,7 @@ export const adminPinnedMessagesApi = {
     formData.append('file', file);
     formData.append('media_type', mediaType);
 
-    const response = await apiClient.post<MediaUploadResponse>('/cabinet/media/upload', formData, {
-      headers: {
-        'Content-Type': 'multipart/form-data',
-      },
-    });
+    const response = await apiClient.post<MediaUploadResponse>('/cabinet/media/upload', formData);
     return response.data;
   },
 };

src/api/branding.ts

@@ -153,11 +153,7 @@ export const brandingApi = {
   uploadLogo: async (file: File): Promise<BrandingInfo> => {
     const formData = new FormData();
     formData.append('file', file);
-    const response = await apiClient.post<BrandingInfo>('/cabinet/branding/logo', formData, {
-      headers: {
-        'Content-Type': 'multipart/form-data',
-      },
-    });
+    const response = await apiClient.post<BrandingInfo>('/cabinet/branding/logo', formData);
     // Invalidate cached blob so it gets re-fetched
     if (_logoBlobUrl) {
       URL.revokeObjectURL(_logoBlobUrl);

src/api/client.ts

@@ -82,6 +82,11 @@ function isAuthEndpoint(url: string | undefined): boolean {
 }
 
 apiClient.interceptors.request.use(async (config: InternalAxiosRequestConfig) => {
+  // Let axios set the correct multipart/form-data header with boundary for FormData
+  if (config.data instanceof FormData && config.headers) {
+    delete config.headers['Content-Type'];
+  }
+
   if (!isAuthEndpoint(config.url)) {
     let token = tokenStorage.getAccessToken();
 

src/api/news.ts

@@ -66,10 +66,7 @@ export const newsApi = {
     const response = await apiClient.post<NewsMediaUploadResponse>(
       '/cabinet/admin/news/media/upload',
       formData,
-      {
-        headers: { 'Content-Type': 'multipart/form-data' },
-        signal,
-      },
+      { signal },
     );
     return response.data;
   },

src/api/tickets.ts

@@ -68,11 +68,7 @@ export const ticketsApi = {
     formData.append('file', file);
     formData.append('media_type', mediaType);
 
-    const response = await apiClient.post<MediaUploadResponse>('/cabinet/media/upload', formData, {
-      headers: {
-        'Content-Type': 'multipart/form-data',
-      },
-    });
+    const response = await apiClient.post<MediaUploadResponse>('/cabinet/media/upload', formData);
     return response.data;
   },