Fix collapsed sheets on macOS across the app

Add macOS-only minimum frame sizing to sheets that wrap a
NavigationStack/Form without intrinsic size, so they render properly
instead of collapsing to just the toolbar. Affects Customize Home,
subscription/channel view options, playlist create/edit, search
filters, media browser options, instance picker, log filters, preset
editor, and legacy data import result.

Yattee/Views/Components/ViewOptionsSheet.swift

@@ -155,6 +155,9 @@ struct ViewOptionsSheet: View {
         .presentationDetents([.height(260)])
         .presentationDragIndicator(.visible)
         #endif
+        #if os(macOS)
+        .frame(minWidth: 420, minHeight: 320)
+        #endif
     }
 }