fix: Fix IOS main file missing during packaging

Author: onion

composeApp/src/iosArm64Main/kotlin/org/onion/diffusion/MainViewController.kt

@@ -0,0 +1,5 @@
+package org.onion.diffusion
+
+import androidx.compose.ui.window.ComposeUIViewController
+
+fun MainViewController() = ComposeUIViewController { App() }