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/gallery/GalleryLayout.tsx

@@ -7,6 +7,7 @@ import { useLocalizedDate } from '../../hooks/useLocalizedDate';
 import { Button } from '../common';
 import { DynamicFavicon } from '../common/DynamicFavicon';
 import { useTheme } from '../../contexts/ThemeContext';
+import { buildResourceUrl } from '../../utils/url';
 
 interface GalleryLayoutProps {
   event: {
@@ -122,7 +123,7 @@ export const GalleryLayout: React.FC<GalleryLayoutProps> = ({
                 <div className="flex-shrink-0">
                   <img 
                     src={brandingSettings?.logo_url ? 
-                      `${import.meta.env.VITE_API_URL || 'http://localhost:3001'}${brandingSettings.logo_url}` : 
+                      buildResourceUrl(brandingSettings.logo_url) : 
                       '/picpeak-logo-transparent.png'
                     } 
                     alt={brandingSettings?.company_name || 'PicPeak'}
@@ -277,7 +278,7 @@ export const GalleryLayout: React.FC<GalleryLayoutProps> = ({
               <div className="mb-6">
                 <img 
                   src={brandingSettings?.logo_url ? 
-                    `${import.meta.env.VITE_API_URL || 'http://localhost:3001'}${brandingSettings.logo_url}` : 
+                    buildResourceUrl(brandingSettings.logo_url) : 
                     '/picpeak-logo-transparent.png'
                   } 
                   alt={brandingSettings?.company_name || 'PicPeak'}