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/Info.plist

@@ -28,5 +28,14 @@
     <array>
         <string>audio</string>
     </array>
+    <key>CFBundleURLTypes</key>
+    <array>
+        <dict>
+            <key>CFBundleURLSchemes</key>
+            <array>
+                <string>marks</string>
+            </array>
+        </dict>
+    </array>
 </dict>
 </plist>