feat: deploy to Frostmoln production

The AWS deploy-prod job has failed since CI left AWS (no k8s.unbound.se
context on the runners). Deploys now go to the Frostmoln production
cluster (namespace sites), the way Shiny deploys to Frostmoln staging.

Frostmoln enforces restricted Pod Security, so the image is
nginx-unprivileged (uid 101, port 8080) with a matching securityContext.
The ALB ingress becomes a Traefik one with a Let's Encrypt certificate.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ma8eHhW59hLAJuLzBnLvUu

.gitea/workflows/ci.yaml

@@ -18,16 +18,30 @@ jobs:
       - name: Build and push
         run: unset GITEA_TOKEN && build && push
 
-  deploy-prod:
+  deploy-prod-frostmoln:
     needs: build
     if: gitea.ref == 'refs/heads/main'
     runs-on: ubuntu-latest
     env:
-      BUILDTOOLS_CONTENT: ${{ secrets.BUILDTOOLS_CONTENT }}
+      BUILDTOOLS_CONTENT: ${{ secrets.BUILDTOOLS_FROSTMOLN_PRODUCTION }}
       GITEA_REPOSITORY: ${{ gitea.repository }}
+      FM_TENANT: 9ae61342-0f76-476f-8176-e46f6b0b0c32
     environment: prod
     steps:
       - uses: actions/checkout@v7
       - uses: buildtool/setup-buildtools-action@v1
-      - name: Deploy to production
-        run: deploy prod
+      - name: Install fm
+        run: |
+          sudo install -d -m 0755 /etc/apt/keyrings
+          sudo curl -fsSL -o /etc/apt/keyrings/frostmoln.gpg https://get.frostmoln.cloud/deb/frostmoln.gpg
+          sudo curl -fsSL -o /etc/apt/sources.list.d/frostmoln.sources https://get.frostmoln.cloud/deb/frostmoln.sources
+          sudo apt-get update && sudo apt-get install -y fm
+      - name: Deploy to Frostmoln production
+        env:
+          FROSTMOLN_API_KEY: ${{ secrets.FROSTMOLN_PRODUCTION_DEPLOY_KEY }}
+        # The cluster API is private: the kubeconfig's exec plugin opens an fm
+        # tunnel on demand. fm reads the key from its config file, not the env.
+        run: |
+          fm auth api-key set "$FROSTMOLN_API_KEY" > /dev/null
+          fm kubernetes cluster kubeconfig ${{ vars.FROSTMOLN_PRODUCTION_CLUSTER_ID }} --exec --file "$RUNNER_TEMP/kubeconfig"
+          KUBECONFIG_CONTENT="$(cat "$RUNNER_TEMP/kubeconfig")" deploy prod-frostmoln -n sites