Add Docker support and environment configuration

Introduced Dockerfile, .dockerignore, and example environment file for containerization. Added compose.yml for Docker Compose setup and renamed docker-compose.dev.yml to compose.dev.yml. Updated build.gradle.kts for Java 21 and shadow plugin, and improved .gitignore and .gitattributes. Refactored Config.java to reorder ENV initialization.

.env.example

@@ -0,0 +1,22 @@
+# Copy this file to .env and customize the values for your environment
+# cp .env.example .env
+
+# Couchbase configuration
+COUCHBASE_CONNECTION_STRING=localhost:8091
+COUCHBASE_USERNAME=admin
+COUCHBASE_PASSWORD=your_password_here
+COUCHBASE_BUCKET_NAME=store_scraper
+
+# Telegram Bot configuration
+TELEGRAM_BOT_TOKEN=your_telegram_bot_token_here
+TELEGRAM_BOT_USERNAME=your_bot_username
+
+# Java configuration
+JAVA_OPTS=-Xmx512m
+
+# Logging configuration
+LOG_LEVEL=INFO
+
+# App configuration
+ENV=DEVELOPMENT
+ADMIN_IDS=1000001999,1000002000,1000002001