ci: update runner-image path to public/ namespace

The runner-image repo moved from libretech/ to public/ on Gitea;
ci.yml and deploy.yml + docs reference public/runner-image.

.gitea/workflows/ci.yml

@@ -10,9 +10,9 @@ jobs:
   ci:
     runs-on: ubuntu-latest
     # Bespoke runner image (Ubuntu 24.04 + make + git + node + go via
-    # actions/setup-go). See git.librete.ch/libretech/runner-image.
+    # actions/setup-go). See git.librete.ch/public/runner-image.
     container:
-      image: git.librete.ch/libretech/runner-image:v2
+      image: git.librete.ch/public/runner-image:v2
     timeout-minutes: 5
     steps:
       - name: Checkout

.gitea/workflows/deploy.yml

@@ -34,7 +34,7 @@ jobs:
     # + perl + ssh, runner user pre-joined to docker gid 998 so the
     # auto-mounted /var/run/docker.sock is writable without --user root.
     container:
-      image: git.librete.ch/libretech/runner-image:v2
+      image: git.librete.ch/public/runner-image:v2
     timeout-minutes: 20
     if: ${{ vars.DEPLOY_ENABLED == 'true' }}
     steps: