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

go.mod

@@ -0,0 +1,5 @@
+module epage
+
+go 1.23
+
+require github.com/joho/godotenv v1.5.1