fix: resolve frontend API routing issues for Traefik deployment

Major fixes for production deployment with Traefik:

1. API Path Fixes:
   - Remove double /api prefix from all frontend service calls
   - Fix auth.service.ts to use correct paths (/auth/admin/login)
   - Update all services to use single /api prefix from base URL
   - Fix template literal paths in photo services

2. Docker Configuration:
   - Add build args for VITE_API_URL in docker-compose.prod.yml
   - Create Dockerfile.prod with proper API URL configuration
   - Ensure frontend is built with correct API base path

3. Documentation:
   - Add comprehensive TRAEFIK_DEPLOYMENT.md guide
   - Document proper Traefik labels and routing configuration
   - Include troubleshooting steps for common issues
   - Explain network configuration and SSL handling

This resolves:
- 502 Bad Gateway errors
- Double /api/api paths in requests
- Frontend unable to communicate with backend
- Login functionality not working

The frontend now correctly calls the backend API through Traefik's
routing, with all requests going to /api/* being forwarded to the
backend service on port 3000.

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

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

frontend/src/utils/photoUrl.ts

@@ -13,7 +13,7 @@ interface PhotoUrlOptions {
 export function getPhotoUrl({ slug, photo, watermarkEnabled = false, token }: PhotoUrlOptions): string {
   if (watermarkEnabled && token) {
     // Use the watermarked photo endpoint
-    return `/api/gallery/${slug}/photo/${photo.id}`;
+    return `/gallery/${slug}/photo/${photo.id}`;
   }
   
   // Use the static photo URL
@@ -24,5 +24,5 @@ export function getPhotoUrl({ slug, photo, watermarkEnabled = false, token }: Ph
  * Get the download URL for a photo
  */
 export function getPhotoDownloadUrl(slug: string, photoId: number): string {
-  return `/api/gallery/${slug}/download/${photoId}`;
+  return `/gallery/${slug}/download/${photoId}`;
 }