feat: Implement S3 presigned URL fetching for user avatars and add an image proxy utility.

src/services/index.ts

@@ -53,3 +53,6 @@ export type {
   CreateFieldDto,
   UpdateFieldDto,
 } from './profile-fields.service';
+
+// Upload Service
+export { uploadService } from './upload.service';

src/services/upload.service.ts

@@ -0,0 +1,27 @@
+import api from './api';
+
+class UploadService {
+  private basePath = '/upload';
+
+  /**
+   * Get a presigned download URL for an S3 key
+   */
+  async getPresignedDownloadUrl(key: string): Promise<string> {
+    const response = await api.get<{ data: { url: string } }>(
+      `${this.basePath}/presigned-download-url`,
+      { params: { key } }
+    );
+    return response.data.data.url;
+  }
+
+  /**
+   * Check if a URL is an S3 key (not a full URL or local path)
+   */
+  isS3Key(url: string | null | undefined): boolean {
+    if (!url) return false;
+    // S3 keys don't start with http or /
+    return !url.startsWith('http') && !url.startsWith('/');
+  }
+}
+
+export const uploadService = new UploadService();