fix: register runner with external URL so job containers can resolve Forgejo

Docker containers launched by the runner on the host cannot resolve
forgejo.forgejo.svc.cluster.local (k8s cluster DNS is not available
from host Docker containers). Switching to https://forgejo.basicstack.de
for runner registration so GITHUB_SERVER_URL in job context uses the
externally reachable URL, fixing git fetch in actions/checkout.

Also adds detection to force re-registration if a pod starts with the
old internal-URL .runner file still present.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/forgejo-runner/forgejo-runner-deployment.yaml

@@ -25,17 +25,23 @@ spec:
         - sh
         - -c
         - |
-          # Wait for Forgejo to be ready
+          # Wait for Forgejo to be ready (external URL)
-          while ! wget -q -O- http://forgejo.forgejo.svc.cluster.local:3000/api/healthz > /dev/null 2>&1; do
+          while ! wget -q -O- https://forgejo.basicstack.de/api/healthz > /dev/null 2>&1; do
             echo "Waiting for Forgejo to be ready..."
             sleep 5
           done
 
+          # Re-register if the stored address is the internal cluster URL
+          if [ -f /data/.runner ] && grep -q "svc.cluster.local" /data/.runner; then
+            echo "Detected internal cluster URL in .runner — forcing re-registration with external URL"
+            rm /data/.runner
+          fi
+
           # Register runner if not already registered
           if [ ! -f /data/.runner ]; then
             forgejo-runner register \
               --no-interactive \
-              --instance http://forgejo.forgejo.svc.cluster.local:3000 \
+              --instance https://forgejo.basicstack.de \
               --token "$RUNNER_TOKEN" \
               --name k3s-runner-1 \
               --labels ubuntu-latest:docker://node:24-bookworm,ubuntu-22.04:docker://node:24-bookworm