Name the server's service ai-app

Accepting this in Dev Updater uninstalls the old ai-app-server unit and
installs and starts ai-app in its place.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.dev-updater.ron

@@ -36,6 +36,7 @@ components: [
         // Resolved against this component's `cwd`, so this is
         // `server/target/release/ai-server`.
         service: Managed("target/release/ai-server"),
+        serviceName: "ai-app",
     ),
     Apk(
         name: "app",