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/firewall.tf

@@ -0,0 +1,16 @@
+// Firewall
+// ----------------------------------
+resource "google_compute_firewall" "allow_http" {
+  name    = "allow-http"
+  network = "default"
+
+  allow {
+    protocol = "tcp"
+    ports = [
+      "80", "443" // http/https
+    ]
+  }
+
+  source_ranges = ["0.0.0.0/0"]
+  target_tags   = ["web"]
+}