fix: mount docker socket at /run not /var/run (symlink issue)

/var/run is a symlink to /run in Alpine. Mounting emptyDir at /var/run
doesn't override the real /run directory, so dind's docker.sock at
/run/docker.sock was never visible to the runner container.

Fix: Mount the shared emptyDir at /run in both containers.

k8s/infra/forgejo-runner/templates/deployment.yaml

@@ -71,7 +71,7 @@ spec:
             - name: docker-certs
               mountPath: /docker-certs
             - name: docker-sock
-              mountPath: /var/run
+              mountPath: /run
             - name: homelab-ca
               mountPath: /etc/ssl/certs/homelab-ca.pem
               subPath: ca.crt
@@ -92,7 +92,7 @@ spec:
             - name: docker-certs
               mountPath: /docker-certs
             - name: docker-sock
-              mountPath: /var/run
+              mountPath: /run
             - name: dind-storage
               mountPath: /var/lib/docker
             - name: homelab-ca