Add Google Cloud K3s infrastructure support

- Add Terraform configuration for GCP instance and storage
- Add startup script for K3s installation and configuration
- Add pipeline scripts for deployment and management
- Add Forgejo deployment manifests and configuration

gcloud/tf/registry.tf

@@ -0,0 +1,14 @@
+// Registry
+// ----------------------------------
+
+// The Artifact Registry repository for our app
+resource "google_artifact_registry_repository" "app-repo" {
+  location      = var.region
+  repository_id = "app-repo"
+  description   = "App Docker repository"
+  format        = "DOCKER"
+
+  docker_config {
+    immutable_tags = true
+  }
+}