Add gitea at git.rubenhensen.nl

Single-pod sqlite install (simplest path for a home git host). HTTPS-only,
no SSH listener for now. Wired into the Hetzner tunnel like the other
rubenhensen.nl services.

First visitor to git.rubenhensen.nl can register; Gitea auto-promotes the
first user to admin.

gitea/gitea-service.yaml

@@ -0,0 +1,13 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: gitea
+  labels:
+    app: gitea
+spec:
+  selector:
+    app: gitea
+  ports:
+    - name: http
+      port: 3000
+      targetPort: 3000