refactor: remove legacy support from Docker and Makefile

Dockerfile changes:
- Replace pip with uv package manager for faster builds
- Remove build-essential and git dependencies
- Use pyproject.toml instead of requirements.txt
- Add uv installation and virtual environment setup
- Modernize environment variables and caching
- Fix hadolint warnings (add --no-install-recommends and pipefail)

Makefile changes:
- Remove docker-build-legacy target (legacy builder)
- Remove docker-dev-host and docker-prod-host targets (networking workarounds)
- Remove docker-reset target (networking fixes)
- Remove docker-clean-legacy target (duplicate functionality)
- Clean up help output and reduce maintenance overhead

This modernizes the build system and removes workarounds for older Docker versions and networking issues.

Makefile

@@ -277,29 +277,18 @@ docker-login: ## Login to container registry (interactive)
 	fi
 	$(call success,Logged into container registry)
 
-docker-build-legacy: ## Build Docker images with legacy builder (networking issues workaround)
-	$(call info,Building Docker images with legacy builder...)
-	DOCKER_BUILDKIT=0 docker-compose build
-	$(call success,Docker images built with legacy builder)
+
 
 docker-dev: ## Start development environment with Docker
 	$(call info,Starting development environment with Docker...)
 	docker-compose up unitforge-dev
 
-docker-dev-host: ## Start development environment with host networking (networking issues workaround)
-	$(call info,Starting development environment with host networking...)
-	docker-compose -f docker-compose.yml -f docker-compose.host-network.yml up unitforge-dev
-
 
 
 docker-prod: ## Start production environment with Docker
 	$(call info,Starting production environment with Docker...)
 	docker-compose up unitforge-prod
 
-docker-prod-host: ## Start production environment with host networking (networking issues workaround)
-	$(call info,Starting production environment with host networking...)
-	docker-compose -f docker-compose.yml -f docker-compose.host-network.yml up unitforge-prod
-
 
 
 docker-cli: ## Run CLI in Docker
@@ -320,18 +309,7 @@ docker-clean: ## Clean up Docker containers and volumes
 	docker system prune -f
 	$(call success,Docker cleanup completed)
 
-docker-reset: ## Reset Docker networking (fix networking issues)
-	$(call info,Resetting Docker networking...)
-	docker network prune -f
-	docker system prune -f
-	sudo systemctl restart docker || echo "Could not restart Docker daemon (requires sudo)"
-	$(call success,Docker networking reset completed)
 
-docker-clean-legacy: ## Clean Docker containers and images
-	$(call info,Cleaning Docker containers and images...)
-	docker-compose down --volumes --remove-orphans
-	docker system prune -f
-	$(call success,Docker cleanup complete)
 
 docker-clean-registry: ## Remove locally cached registry images
 	$(call info,Cleaning registry images from local cache...)