bootstrap: use base images for runners, custom images via CI

- golang-runner: docker:27-cli (has Node.js + docker)
- rust-runner: docker:27-cli (bootstrap, CI adds Rust)
- node-runner: node:22-bookworm (has Node.js, CI adds docker)

CI workflow (.gitea/workflows/build-runner-images.yml):
1. Watches Dockerfile.* changes
2. Builds custom images with Node.js pre-installed
3. Pushes to registry
4. Image Updater detects and updates values.yaml
5. ArgoCD syncs to new custom images

This avoids token complexity - just push Dockerfile changes to git!

k8s/infra/forgejo-runner/values-node.yaml

@@ -4,13 +4,13 @@
 #
 # node:22-bookworm ships Node natively. Docker client installed via workflow step if needed.
 # (homelab has no CI; custom runner images built manually if desired)
+# Bootstrap with base image, custom image via CI+Image Updater
 runner:
   image:
-    repository: forgejo.riotpiao.com/rock/forgejo-runner-node
-    tag: "latest"  # Image Updater tracks and updates this
+    repository: node
+    tag: "22-bookworm"
   name: node-runner
-  # Custom image: node:22-bookworm + docker.io pre-installed
-  labels: "node:docker://forgejo.riotpiao.com/rock/forgejo-runner-node:latest"
+  labels: "node:docker://node:22-bookworm"
 
 # GC CronJob renders only from the default (golang) values to avoid duplicates
 gc: