Fix ShareExtension "Open Marks first" + add widget + BookmarkListRow polish

- Save serverConfig to App Group on every app launch so ShareExtension
  can always find credentials without requiring a disconnect/reconnect flow
- Add MarksWidget target with RandomBookmarkWidget (random saved bookmark,
  reloads hourly) using file-based App Group storage to avoid CFPreferences issues
- Extract BookmarkListRow as shared component with editorial typography tweaks
  (17pt semibold title, 13pt domain, relative date, 32×32 favicon, italic AI summary,
  20pt podcast icon, 16pt horizontal insets)
- Add MarksWidget and ShareExtension Xcode schemes for direct run/debug

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Marks/Views/BookmarksViewModel.swift

@@ -39,6 +39,9 @@ final class BookmarksViewModel {
             nextPageUrl = response.next
             restoreAIData()
             saveToCache(bookmarks)
+            WidgetDataStore.saveBookmarks(bookmarks.prefix(20).map {
+                WidgetBookmark(url: $0.url, title: $0.displayTitle, domain: $0.domain, faviconUrl: $0.faviconUrl)
+            })
         } catch {
             self.error = error.localizedDescription
         }