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/Services/PodcastIndex.swift

@@ -6,6 +6,7 @@ struct PodcastEntry: Codable, Identifiable {
     let filename: String
     var title: String?
     let createdAt: Date
+    var parentBookmarkUrl: String?
 }
 
 enum PodcastIndex {
@@ -35,14 +36,19 @@ enum PodcastIndex {
         return entries.sorted { $0.createdAt > $1.createdAt }
     }
 
-    static func upsert(articleUrl: String, filename: String, title: String?) {
+    static func upsert(articleUrl: String, filename: String, title: String?, parentBookmarkUrl: String? = nil) {
         var entries = all()
         entries.removeAll { $0.articleUrl == articleUrl }
         entries.insert(PodcastEntry(articleUrl: articleUrl, filename: filename,
-                                    title: title, createdAt: Date()), at: 0)
+                                    title: title, createdAt: Date(),
+                                    parentBookmarkUrl: parentBookmarkUrl), at: 0)
         save(entries)
     }
 
+    static func find(for bookmarkUrl: String) -> [PodcastEntry] {
+        all().filter { $0.parentBookmarkUrl == bookmarkUrl || $0.articleUrl == bookmarkUrl }
+    }
+
     static func remove(articleUrl: String) {
         var entries = all()
         entries.removeAll { $0.articleUrl == articleUrl }
@@ -52,5 +58,8 @@ enum PodcastIndex {
     private static func save(_ entries: [PodcastEntry]) {
         guard let data = try? encoder.encode(entries) else { return }
         try? data.write(to: indexURL, options: .atomic)
+        WidgetDataStore.savePodcasts(entries.prefix(10).map {
+            WidgetPodcast(articleUrl: $0.articleUrl, title: $0.title ?? $0.articleUrl, createdAt: $0.createdAt)
+        })
     }
 }