fix(cicd): isolate pull request runner jobs

.gitea/runner/pr-runner.service

@@ -0,0 +1,27 @@
+[Unit]
+Description=Gitea Actions untrusted pull request runner
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+User=gitea-pr-runner
+Group=gitea-pr-runner
+WorkingDirectory=/var/lib/gitea-pr-runner
+Environment=HOME=/var/lib/gitea-pr-runner
+Environment=PATH=/var/lib/gitea-pr-runner/.cache/homelab-ci/bin:/usr/local/bin:/usr/bin:/bin
+ExecStart=/usr/local/bin/gitea-runner daemon --config /etc/gitea-pr-runner/config.yaml
+Restart=on-failure
+RestartSec=5
+NoNewPrivileges=yes
+PrivateTmp=yes
+ProtectSystem=full
+ProtectHome=yes
+ProtectKernelTunables=yes
+ProtectKernelModules=yes
+ProtectControlGroups=yes
+RestrictSUIDSGID=yes
+LockPersonality=yes
+UMask=0077
+
+[Install]
+WantedBy=multi-user.target