fix: use proper language images for runner labels, not bare Alpine

ROOT CAUSE: All 3 runner labels pointed to code.forgejo.org/forgejo/runner:6
(bare Alpine). When Forgejo runs a workflow, it creates a container FROM the
label image — this container had no Node.js, no docker CLI, no Go/Rust,
no root access, and no apt-get. Every CI job failed.

FIX: Change runner labels to official Debian-based language images:
  golang → docker://golang:1.26-bookworm (Go + apt-get + root)
  node   → docker://node:22-bookworm (Node.js + npm + apt-get + root)
  rust   → docker://rust:1-bookworm (Rust + cargo + apt-get + root)

The runner daemon pod still uses forgejo/runner:6 — only the label image
(what workflow steps execute in) changes.

Unified CI pattern for ALL repos:
1. Install Node.js first if not present (needed for actions/checkout@v4)
2. Install docker.io via apt-get (needed for docker build/push)
3. Use actions/checkout@v4 normally
4. Build/push with docker

IMPORTANT: Runners must re-register after merge. Delete PVCs or
/data/.runner files to trigger re-registration with new labels.

.gitea/workflows/build-runner-images.yml

@@ -18,13 +18,16 @@ on:
 jobs:
   build-runners:
     runs-on: golang
-    env:
-      REGISTRY: forgejo.riotpiao.com
-      IMAGE_BASE: forgejo.riotpiao.com/rock
+    # Unified CI pattern: golang label → golang:1.26-bookworm (Debian, root, apt-get)
+    # Install Node.js + docker in steps. actions/checkout@v4 needs Node.js.
     steps:
-      - name: Clone repository
+      - name: Install dependencies
         run: |
-          git clone --depth 1 https://forgejo.riotpiao.com/rock/homelab.git .
+          apt-get update
+          apt-get install -y --no-install-recommends nodejs docker.io
+          rm -rf /var/lib/apt/lists/*
+
+      - uses: actions/checkout@v4
 
       - name: Get commit SHA
         id: sha
@@ -32,7 +35,7 @@ jobs:
           SHORT_SHA=$(git rev-parse --short HEAD)
           echo "short_sha=${SHORT_SHA}" >> $GITHUB_OUTPUT
 
-      - name: Build all runner images (test on PR, push on main)
+      - name: Build all runner images
         run: |
           set -e
           for RUNNER in golang rust node; do
@@ -50,7 +53,6 @@ jobs:
           echo "${REGISTRY_TOKEN}" | docker login "${REGISTRY}" \
             --username "${REGISTRY_USER}" --password-stdin
           for RUNNER in golang rust node; do
-            echo "📤 Pushing ${RUNNER}-runner:${{ steps.sha.outputs.short_sha }}"
             docker push "${IMAGE_BASE}/forgejo-runner-${RUNNER}:${{ steps.sha.outputs.short_sha }}"
             docker push "${IMAGE_BASE}/forgejo-runner-${RUNNER}:latest"
             echo "✅ Pushed ${RUNNER}-runner"
@@ -58,3 +60,6 @@ jobs:
         env:
           REGISTRY_USER: ${{ secrets.FORGEJO_REGISTRY_USER }}
           REGISTRY_TOKEN: ${{ secrets.FORGEJO_REGISTRY_TOKEN }}
+    env:
+      REGISTRY: forgejo.riotpiao.com
+      IMAGE_BASE: forgejo.riotpiao.com/rock