Migrate from Redis to Couchbase for data storage

Replaces Redis with Couchbase as the primary data store. Updates environment variables, dependencies, and Docker Compose configuration to use Couchbase. Refactors repository and model classes to use Couchbase APIs, removes Redis utility and related code, and adds Couchbase utility for collection management. Updates AdminRepository to use 'admin' as the key instead of an empty string.

.env.example

@@ -1,8 +1,11 @@
 # Copy this file to .env and customize the values for your environment
 # cp .env.example .env
 
-# Redis configuration
-REDIS_URL=localhost:6379
+# Couchbase configuration
+COUCHBASE_CONNECTION_STRING=couchbase://localhost
+COUCHBASE_USERNAME=admin
+COUCHBASE_PASSWORD=your_password_here
+COUCHBASE_BUCKET_NAME=store_scraper
 
 # Telegram Bot configuration
 TELEGRAM_BOT_TOKEN=your_telegram_bot_token_here