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.

Dockerfile

@@ -11,6 +11,9 @@ RUN pip install --no-cache-dir -r requirements.txt
 # Copy application code
 COPY . .
 
+# Dashboard (Flask) port
+EXPOSE 8080
+
 # Create a non-root user
 RUN addgroup -S appgroup && adduser -S appuser -G appgroup
 USER appuser