Migrate storage from JSON to SQLite with enhanced MVC architecture

- Replace JSON file storage with SQLite database for improved concurrency and data integrity
- Implement repository pattern with dedicated model layer (admin_model, file_model, chunk_model)
- Add database.py with automatic migration from existing JSON files
- Enable WAL mode for thread-safe concurrent access across Gunicorn workers
- Store database files in dedicated db/ folder
- Update controllers to use model layer instead of direct JSON access
- Add admin authentication system with TOTP 2FA support

src/app.py

@@ -1,5 +1,6 @@
 import os
 from functools import wraps
+from datetime import timedelta
 from flask import Flask, request, jsonify, send_from_directory
 from werkzeug.utils import secure_filename
 import utils.mLogger as log
@@ -8,15 +9,26 @@ from controllers.file_controller import (
     start_chunked_upload, upload_chunk, verify_chunks, complete_chunked_upload,
     cleanup_expired_files, cleanup_abandoned_uploads
 )
+from controllers.admin_controller import (
+    setup_admin, setup_admin_totp, admin_login, admin_dashboard, admin_logout
+)
 from views import views
+from models import init_db, migrate_from_json
 
 app = Flask(__name__)
 app.config['UPLOAD_FOLDER'] = 'tmp/uploads'
 app.config['CLIENT_KEY'] = os.environ.get('CLIENT_KEY', 'default-secret-key')
+app.config['SECRET_KEY'] = os.environ.get('SECRET_KEY', os.urandom(24).hex())
+app.config['PERMANENT_SESSION_LIFETIME'] = timedelta(hours=24)
 
 if not os.path.exists(app.config['UPLOAD_FOLDER']):
     os.makedirs(app.config['UPLOAD_FOLDER'])
 
+# Initialize database
+log.i("Initializing database...")
+init_db()
+migrate_from_json()
+
 # Run cleanup on startup
 cleanup_expired_files()
 cleanup_abandoned_uploads()
@@ -53,6 +65,13 @@ app.route('/download/<code>', methods=['GET'])(download_file)
 # Route for deleting the file
 app.route('/delete/<code>', methods=['DELETE'])(delete_file)
 
+# Admin routes
+app.route('/admin/setup', methods=['GET', 'POST'], endpoint='setup_admin')(setup_admin)
+app.route('/admin/setup/totp', methods=['GET', 'POST'], endpoint='setup_admin_totp')(setup_admin_totp)
+app.route('/admin/login', methods=['GET', 'POST'], endpoint='admin_login')(admin_login)
+app.route('/admin', methods=['GET'], endpoint='admin_dashboard')(admin_dashboard)
+app.route('/admin/logout', methods=['GET'], endpoint='admin_logout')(admin_logout)
+
 # Register frontend views
 app.register_blueprint(views)