fix: remove hardcoded localhost URLs for production deployment

- Add URL utility functions for building resource URLs
- Update all components to use relative URLs in production
- Add production deployment documentation
- Update nginx config to proxy all required endpoints
- Add .env.production.example with proper configuration

frontend/src/components/common/AuthenticatedImage.tsx

@@ -1,5 +1,6 @@
 import React, { useState, useEffect } from 'react';
 import { getAuthToken } from '../../config/api';
+import { buildResourceUrl } from '../../utils/url';
 
 interface AuthenticatedImageProps extends React.ImgHTMLAttributes<HTMLImageElement> {
   src: string;
@@ -60,9 +61,8 @@ export const AuthenticatedImage: React.FC<AuthenticatedImageProps> = ({
         // Use the src as-is since it should already be the correct endpoint
         let imageUrl = src;
         
-        // Prepend API URL for absolute paths
-        const apiUrl = import.meta.env.VITE_API_URL || 'http://localhost:3001';
-        const fullImageUrl = imageUrl.startsWith('/') ? `${apiUrl}${imageUrl}` : imageUrl;
+        // Build full URL for the image
+        const fullImageUrl = imageUrl.startsWith('/') ? buildResourceUrl(imageUrl) : imageUrl;
         
         console.log('Fetching authenticated image:', fullImageUrl);
         const response = await fetch(fullImageUrl, {