Publish live-update manifest to fileserver (dev)

After pushing the dev closure to Attic, write a small JSON manifest
(version + storePath) to the fileserver for kiosks to poll. storePath is
the readlink of the result-pkg out-link, so it matches exactly the
closure pushed to the dev Attic cache and can be fetched with
'nix copy --from' without building from source. Upload goes to
/mnt/infrastructure_data/files/radiantwave-dev/manifest.json via the
build-server's radiantwave-infra SSH alias.

.gitea/workflows/dev.yml

@@ -66,3 +66,17 @@ jobs:
         run: |
           attic login radiantwave https://attic.radiantwavetech.com "$ATTIC_TOKEN"
           attic push radiantwave:radiantwave-dev ./result-pkg
+
+      # Publish the manifest kiosks poll for live app updates. `storePath`
+      # must match exactly the closure pushed to the dev Attic cache above
+      # (readlink resolves the result-pkg out-link symlink to its real
+      # /nix/store path), so a kiosk can `nix copy --from` it without ever
+      # building from source. Upload mirrors the ISO scp pattern to the
+      # fileserver via the build-server's `radiantwave-infra` SSH alias.
+      - name: Publish manifest
+        run: |
+          STOREPATH=$(readlink -f ./result-pkg)
+          printf '{"version":"%s","storePath":"%s"}\n' "${{ env.APP_VERSION }}" "$STOREPATH" > manifest.json
+          cat manifest.json
+          scp manifest.json \
+            radiantwave-infra:/mnt/infrastructure_data/files/radiantwave-dev/manifest.json