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.xcodeproj/xcshareddata/xcschemes/Marks.xcscheme

@@ -21,6 +21,20 @@
                ReferencedContainer = "container:Marks.xcodeproj">
             </BuildableReference>
          </BuildActionEntry>
+         <BuildActionEntry
+            buildForTesting = "YES"
+            buildForRunning = "YES"
+            buildForProfiling = "YES"
+            buildForArchiving = "YES"
+            buildForAnalyzing = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "61046BF39C48393DD96687A0"
+               BuildableName = "MarksWidget.appex"
+               BlueprintName = "MarksWidget"
+               ReferencedContainer = "container:Marks.xcodeproj">
+            </BuildableReference>
+         </BuildActionEntry>
          <BuildActionEntry
             buildForTesting = "YES"
             buildForRunning = "YES"