feat: add missing flush

src/main.zig

@@ -113,6 +113,7 @@ pub fn main() !u8 {
     var stdout_writer = std.fs.File.stdout().writer(&stdout_buffer);
     const stdout = &stdout_writer.interface;
     _ = try stdout.write(try std.fmt.allocPrint(allocator, "{d}\n", .{selected_app.id}));
+    try stdout.flush();
 
     return 0;
 }