feat: funciones infra — Docker, deploy, build y health check

Funciones impuras para gestión de contenedores: docker_build_image,
docker_compose_up/down, docker_volume_create/list/remove,
generate_dockerfile, write_dockerfile, go_build_binary, health_check_http,
deploy_app y stop_app. Todas con tests unitarios donde aplica.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

functions/infra/docker_volume_create.go

@@ -0,0 +1,17 @@
+package infra
+
+import (
+	"fmt"
+	"os/exec"
+	"strings"
+)
+
+// DockerVolumeCreate crea un volume Docker con el nombre dado.
+// Retorna el nombre del volume creado.
+func DockerVolumeCreate(name string) (string, error) {
+	out, err := exec.Command("docker", "volume", "create", name).CombinedOutput()
+	if err != nil {
+		return "", fmt.Errorf("docker volume create %s: %s", name, strings.TrimSpace(string(out)))
+	}
+	return strings.TrimSpace(string(out)), nil
+}