Write the build command as a line

Both forms parse to the same argv; the line is what this one reads best
as. See dev-updater's commit for the boundary conversion.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QQz6R4kBQcWSHBNZMgBnjL

app/.dev-updater.ron

@@ -8,5 +8,5 @@ package: "com.example.aiapp",
 label: "AI Sessions",
 
 prepare: (
-    command: ["./build-apk.sh"],
+    command: "./build-apk.sh",
 ),