Present view options and search filters as popovers on macOS

Plain-Form sheets rendered as columns-style content floating inside
oversized fixed frames on macOS. Anchor these panels to their toolbar
buttons as popovers instead, sized to content; iOS/tvOS keep sheets.

- Search and PeerTube explore filters apply live (Cancel never
  reverted anything anyway) and dismiss on outside click
- Subscriptions/Manage Channels "Subscriptions Data" opens as a sheet
  from the popover's onDisappear via a pending flag, since presenting
  while the popover dismisses gets swallowed
- Media browser view options drop navigation chrome on macOS

Yattee/Views/MediaBrowser/MediaBrowserViewOptionsSheet.swift

@@ -21,26 +21,43 @@ struct MediaBrowserViewOptionsSheet: View {
     }
 
     var body: some View {
+        #if os(macOS)
+        // Popover content: no navigation chrome, click-outside dismisses.
+        formContent
+            .padding()
+            .frame(width: 300)
+            .onAppear {
+                // Reset sort order if current selection is not available for this source type
+                if !availableSortOptions.contains(sortOrder) {
+                    sortOrder = .name
+                }
+            }
+        #else
         NavigationStack {
             #if os(tvOS)
             listContent
             #else
             formContent
+                .navigationTitle("mediaBrowser.viewOptions.title")
+                #if os(iOS)
+                .navigationBarTitleDisplayMode(.inline)
+                #endif
+                .toolbar {
+                    sheetCloseToolbarItem { dismiss() }
+                }
             #endif
         }
         #if os(iOS)
         .presentationDetents([.height(280)])
         .presentationDragIndicator(.visible)
         #endif
-        #if os(macOS)
-        .frame(minWidth: 420, minHeight: 320)
-        #endif
         .onAppear {
             // Reset sort order if current selection is not available for this source type
             if !availableSortOptions.contains(sortOrder) {
                 sortOrder = .name
             }
         }
+        #endif
     }
 
     @ViewBuilder
@@ -83,13 +100,6 @@ struct MediaBrowserViewOptionsSheet: View {
                 sharedOptions
             }
         }
-        .navigationTitle("mediaBrowser.viewOptions.title")
-        #if os(iOS)
-        .navigationBarTitleDisplayMode(.inline)
-        #endif
-        .toolbar {
-            sheetCloseToolbarItem { dismiss() }
-        }
     }
 }