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.

.env.example

@@ -0,0 +1,29 @@
+# Flask
+FLASK_ENV=development
+FLASK_DEBUG=1
+SECRET_KEY=change-me-in-production
+
+# Redis
+REDIS_URL=redis://redis:6379/0
+
+# Celery
+CELERY_BROKER_URL=redis://redis:6379/0
+CELERY_RESULT_BACKEND=redis://redis:6379/1
+
+# AWS S3
+AWS_ACCESS_KEY_ID=your-access-key
+AWS_SECRET_ACCESS_KEY=your-secret-key
+AWS_S3_BUCKET=saas-pdf-temp-files
+AWS_S3_REGION=eu-west-1
+
+# File Processing
+MAX_CONTENT_LENGTH_MB=50
+UPLOAD_FOLDER=/tmp/uploads
+OUTPUT_FOLDER=/tmp/outputs
+FILE_EXPIRY_SECONDS=1800
+
+# CORS
+CORS_ORIGINS=http://localhost:5173,http://localhost:3000
+
+# AdSense
+ADSENSE_CLIENT_ID=ca-pub-XXXXXXXXXXXXXXXX