Add initial implementation of ePage application with Docker support

- Create main application logic with HTTP handlers for form submissions
- Implement Pushover API integration for sending messages
- Add unit tests for handlers and Pushover payload structure
- Include Dockerfile and docker-compose configuration for easy deployment
- Add example environment file and update README with setup instructions
- Create HTML templates for user interface

docker-compose.yml

@@ -0,0 +1,14 @@
+version: '3.8'
+
+services:
+  epage:
+    build: .
+    ports:
+      - "5000:5000"
+    environment:
+      - PUSHOVER_API_TOKEN=${PUSHOVER_API_TOKEN}
+      - PUSHOVER_USER_KEY=${PUSHOVER_USER_KEY}
+      - PORT=5000
+    volumes:
+      - ./templates:/root/templates
+      - ./static:/root/static