feat: Initialize frontend with React, Vite, and Tailwind CSS

- Set up main entry point for React application.
- Create About, Home, NotFound, Privacy, and Terms pages with SEO support.
- Implement API service for file uploads and task management.
- Add global styles using Tailwind CSS.
- Create utility functions for SEO and text processing.
- Configure Vite for development and production builds.
- Set up Nginx configuration for serving frontend and backend.
- Add scripts for cleanup of expired files and sitemap generation.
- Implement deployment script for production environment.

nginx/nginx.conf

@@ -0,0 +1,48 @@
+upstream backend {
+    server backend:5000;
+}
+
+upstream frontend {
+    server frontend:5173;
+}
+
+server {
+    listen 80;
+    server_name localhost;
+    client_max_body_size 100M;
+
+    # Security headers
+    add_header X-Frame-Options "SAMEORIGIN" always;
+    add_header X-Content-Type-Options "nosniff" always;
+    add_header X-XSS-Protection "1; mode=block" always;
+    add_header Referrer-Policy "strict-origin-when-cross-origin" always;
+
+    # API requests → Flask backend
+    location /api/ {
+        proxy_pass http://backend;
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        proxy_set_header X-Forwarded-Proto $scheme;
+
+        # Timeout for large file uploads
+        proxy_read_timeout 300s;
+        proxy_send_timeout 300s;
+        proxy_connect_timeout 60s;
+    }
+
+    # Frontend (Vite dev server in dev, static in prod)
+    location / {
+        proxy_pass http://frontend;
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        proxy_set_header Upgrade $http_upgrade;
+        proxy_set_header Connection "upgrade";
+    }
+
+    # Health check
+    location /health {
+        proxy_pass http://backend/api/health;
+    }
+}