Implement calendar display application

Built a full-featured smart display app with Flask backend and responsive frontend.

Features:
- Real-time clock display
- Weather integration (OpenWeatherMap API) for Hamilton, NZ
- Google Calendar integration (placeholder, needs credentials)
- Rotating background images from local directory
- Dad jokes display (icanhazdadjoke API)

Technical stack:
- Backend: Python Flask with API endpoints
- Frontend: HTML/CSS/JavaScript with auto-updating data
- Caching system to avoid API rate limits
- Responsive design for various screen sizes

Deployment ready for Raspberry Pi with systemd service and Chromium kiosk mode setup instructions.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

.env.example

@@ -0,0 +1,20 @@
+# Flask Configuration
+FLASK_SECRET_KEY=your_secret_key_here
+
+# OpenWeatherMap API
+OPENWEATHER_API_KEY=your_api_key_here
+
+# Weather Location (Hamilton, New Zealand)
+WEATHER_LOCATION=Hamilton,NZ
+WEATHER_LAT=-37.7870
+WEATHER_LON=175.2793
+
+# Google Calendar
+GOOGLE_CALENDAR_ID=your_calendar_id@group.calendar.google.com
+
+# Update Intervals (seconds)
+IMAGE_ROTATION_INTERVAL=300
+WEATHER_UPDATE_INTERVAL=900
+CALENDAR_UPDATE_INTERVAL=300
+JOKE_UPDATE_INTERVAL=3600
+CALENDAR_DAYS_AHEAD=7