feat: Add dashboard support and enhance Discord webhook functionality

- Updated docker-compose.yml to expose dashboard on port 8080.
- Enhanced main.py with timezone database caching and improved state management.
- Introduced a minimal dashboard using Flask to display webhook status and notifications.
- Added templates.json for customizable embed messages in Discord notifications.
- Created templates.py for loading and saving notification templates.
- Implemented tests for dashboard rendering and main functionality.
- Added requirements for Flask and tzdata to support new features.
- Included test cases for timezone handling and template management.

docker-compose.yml

@@ -4,7 +4,10 @@ services:
     container_name: thc-webhook-app
     environment:
       - DISCORD_WEBHOOK_URL=${DISCORD_WEBHOOK_URL}
+      - DASHBOARD_PORT=8080
     restart: unless-stopped
+    ports:
+      - "8080:8080"
     logging:
       driver: json-file
       options: