build: add docker support

- Add Dockerfile for containerized deployment
- Add .drone.yml for CI/CD pipeline configuration
- Add docker and docker-run targets to Makefile
- Configure port 8080 binding and persistent volume mount

Makefile

@@ -1,4 +1,4 @@
-.PHONY: all frontend backend clean dev docker docker-run
+.PHONY: all frontend backend clean dev docker docker-run tests
 
 all: frontend backend
 
@@ -21,3 +21,6 @@ docker:
 
 docker-run:
 	docker run -p 8080:8080 -v aethera-data:/app/data aethera
+
+tests:
+	cd backend && go test ./...