Replace Slint UI with UIKit and add milestones

Fixes #2.\nFixes #9.

ios/Generated/gotcha_core.modulemap

@@ -0,0 +1,7 @@
+module gotcha_core {
+    header "gotcha_coreFFI.h"
+    export *
+    use "Darwin"
+    use "_Builtin_stdbool"
+    use "_Builtin_stdint"
+}