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.

backend/app/extensions.py

@@ -0,0 +1,43 @@
+"""Flask extensions initialization."""
+from celery import Celery
+from flask_cors import CORS
+from flask_limiter import Limiter
+from flask_limiter.util import get_remote_address
+from flask_talisman import Talisman
+
+# Initialize extensions (will be bound to app in create_app)
+cors = CORS()
+limiter = Limiter(key_func=get_remote_address)
+talisman = Talisman()
+celery = Celery()
+
+
+def init_celery(app):
+    """Initialize Celery with Flask app context."""
+    celery.conf.broker_url = app.config["CELERY_BROKER_URL"]
+    celery.conf.result_backend = app.config["CELERY_RESULT_BACKEND"]
+    celery.conf.result_expires = app.config.get("FILE_EXPIRY_SECONDS", 1800)
+    celery.conf.task_serializer = "json"
+    celery.conf.result_serializer = "json"
+    celery.conf.accept_content = ["json"]
+    celery.conf.timezone = "UTC"
+    celery.conf.task_track_started = True
+
+    # Set task routes
+    celery.conf.task_routes = {
+        "app.tasks.convert_tasks.*": {"queue": "convert"},
+        "app.tasks.compress_tasks.*": {"queue": "compress"},
+        "app.tasks.image_tasks.*": {"queue": "image"},
+        "app.tasks.video_tasks.*": {"queue": "video"},
+    }
+
+    class ContextTask(celery.Task):
+        """Make Celery tasks work with Flask app context."""
+        abstract = True
+
+        def __call__(self, *args, **kwargs):
+            with app.app_context():
+                return self.run(*args, **kwargs)
+
+    celery.Task = ContextTask
+    return celery