test that flutter_rust_bridge works

flutter_app/rust/src/api/simple.rs

@@ -0,0 +1,10 @@
+#[flutter_rust_bridge::frb(sync)] // Synchronous mode for simplicity of the demo
+pub fn greet(name: String) -> String {
+    format!("Hello, {name}!")
+}
+
+#[flutter_rust_bridge::frb(init)]
+pub fn init_app() {
+    // Default utilities - feel free to customize
+    flutter_rust_bridge::setup_default_user_utils();
+}