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/Settings/InstancePickerSheet.swift

@@ -65,6 +65,9 @@ struct InstancePickerSheet: View {
             }
         }
         .presentationDetents([.medium, .large])
+        #if os(macOS)
+        .frame(minWidth: 450, minHeight: 500)
+        #endif
     }
 }
 

Yattee/Views/Settings/LegacyDataImportView.swift

@@ -219,6 +219,9 @@ struct LegacyDataImportView: View {
             .padding()
             .interactiveDismissDisabled()
         }
+        #if os(macOS)
+        .frame(minWidth: 500, minHeight: 450)
+        #endif
     }
 
     // MARK: - Actions

Yattee/Views/Settings/LogViewerView.swift

@@ -308,6 +308,9 @@ private struct LogFiltersSheet: View {
             }
         }
         .presentationDetents([.medium])
+        #if os(macOS)
+        .frame(minWidth: 500, minHeight: 500)
+        #endif
     }
 
     private func binding(for category: LogCategory) -> Binding<Bool> {

Yattee/Views/Settings/PlayerControls/PresetEditorView.swift

@@ -145,6 +145,9 @@ struct PresetEditorView: View {
         #if os(iOS)
         .presentationDetents([.medium])
         #endif
+        #if os(macOS)
+        .frame(minWidth: 500, minHeight: 350)
+        #endif
     }
 
     private func saveIfValid() {