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/routes/convert.py

@@ -0,0 +1,73 @@
+"""PDF conversion routes (PDF↔Word)."""
+from flask import Blueprint, request, jsonify
+
+from app.extensions import limiter
+from app.utils.file_validator import validate_file, FileValidationError
+from app.utils.sanitizer import generate_safe_path
+from app.tasks.convert_tasks import convert_pdf_to_word, convert_word_to_pdf
+
+convert_bp = Blueprint("convert", __name__)
+
+
+@convert_bp.route("/pdf-to-word", methods=["POST"])
+@limiter.limit("10/minute")
+def pdf_to_word_route():
+    """
+    Convert a PDF file to Word (DOCX).
+
+    Accepts: multipart/form-data with 'file' field (PDF)
+    Returns: JSON with task_id for polling
+    """
+    if "file" not in request.files:
+        return jsonify({"error": "No file provided."}), 400
+
+    file = request.files["file"]
+
+    try:
+        original_filename, ext = validate_file(file, allowed_types=["pdf"])
+    except FileValidationError as e:
+        return jsonify({"error": e.message}), e.code
+
+    # Save file to temp location
+    task_id, input_path = generate_safe_path(ext, folder_type="upload")
+    file.save(input_path)
+
+    # Dispatch async task
+    task = convert_pdf_to_word.delay(input_path, task_id, original_filename)
+
+    return jsonify({
+        "task_id": task.id,
+        "message": "Conversion started. Poll /api/tasks/{task_id}/status for progress.",
+    }), 202
+
+
+@convert_bp.route("/word-to-pdf", methods=["POST"])
+@limiter.limit("10/minute")
+def word_to_pdf_route():
+    """
+    Convert a Word (DOC/DOCX) file to PDF.
+
+    Accepts: multipart/form-data with 'file' field (DOC/DOCX)
+    Returns: JSON with task_id for polling
+    """
+    if "file" not in request.files:
+        return jsonify({"error": "No file provided."}), 400
+
+    file = request.files["file"]
+
+    try:
+        original_filename, ext = validate_file(
+            file, allowed_types=["doc", "docx"]
+        )
+    except FileValidationError as e:
+        return jsonify({"error": e.message}), e.code
+
+    task_id, input_path = generate_safe_path(ext, folder_type="upload")
+    file.save(input_path)
+
+    task = convert_word_to_pdf.delay(input_path, task_id, original_filename)
+
+    return jsonify({
+        "task_id": task.id,
+        "message": "Conversion started. Poll /api/tasks/{task_id}/status for progress.",
+    }), 202