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, {

frontend/src/components/common/DynamicFavicon.tsx

@@ -1,12 +1,13 @@
 import { useEffect } from 'react';
 import { useQuery } from '@tanstack/react-query';
+import { getApiBaseUrl, buildResourceUrl } from '../../utils/url';
 
 export const DynamicFavicon: React.FC = () => {
   const { data: settings } = useQuery({
     queryKey: ['public-settings'],
     queryFn: async () => {
       try {
-        const response = await fetch(`${import.meta.env.VITE_API_URL || 'http://localhost:3001'}/api/public/settings`);
+        const response = await fetch(`${getApiBaseUrl()}/public/settings`);
         if (response.ok) {
           return response.json();
         }
@@ -30,7 +31,7 @@ export const DynamicFavicon: React.FC = () => {
       link.type = 'image/png';
       link.href = settings.branding_favicon_url.startsWith('http') 
         ? settings.branding_favicon_url 
-        : `${import.meta.env.VITE_API_URL || 'http://localhost:3001'}${settings.branding_favicon_url}`;
+        : buildResourceUrl(settings.branding_favicon_url);
       
       document.head.appendChild(link);
     }

frontend/src/components/common/ReCaptcha.tsx

@@ -1,6 +1,7 @@
 import React, { useEffect, useState } from 'react';
 import ReCAPTCHA from 'react-google-recaptcha';
 import { useQuery } from '@tanstack/react-query';
+import { getApiBaseUrl } from '../../utils/url';
 
 interface ReCaptchaProps {
   onChange: (token: string | null) => void;
@@ -20,7 +21,7 @@ export const ReCaptcha: React.FC<ReCaptchaProps> = ({
   const { data: settings } = useQuery({
     queryKey: ['public-settings'],
     queryFn: async () => {
-      const response = await fetch(`${import.meta.env.VITE_API_URL || 'http://localhost:3001'}/api/public/settings`);
+      const response = await fetch(`${getApiBaseUrl()}/public/settings`);
       return response.json();
     },
     staleTime: 5 * 60 * 1000, // Cache for 5 minutes