Add per-page element customization and panel settings polish

Phase 5 of the player panels redesign:
- Per-page element toggles now rendered and editable for every page:
  comments (author avatars), related (thumbnails), chapters (thumbnails),
  queue (previously played section), tracks (video/audio/subtitles/speed
  sections)
- Page bar labels toggle (icons-only bar shows the selected page's name)
- Layout mode schematic diagram in the details panel settings
- NEW badge machinery for future page types (versionAdded on PanelPageType)
- Typed per-page settings accessors on PanelPageConfiguration and VM update
  helpers for each page kind
- Unit tests for per-page settings round-trip and accessor fallbacks

The standalone quality selector sheet is unaffected: section gating defaults
to everything visible and only the embedded tracks page passes preset
settings through.

Yattee/Views/Components/ExpandedCommentsView.swift

@@ -255,6 +255,7 @@ struct CommentsListContent: View {
     @Environment(\.appEnvironment) private var appEnvironment
 
     let videoID: String
+    var showAvatars: Bool = true
 
     private var playerState: PlayerState? { appEnvironment?.playerService.state }
     private var contentService: ContentService? { appEnvironment?.contentService }
@@ -318,7 +319,7 @@ struct CommentsListContent: View {
             } else {
                 LazyVStack(alignment: .leading, spacing: 0) {
                     ForEach(comments) { comment in
-                        CommentView(comment: comment, videoID: videoID, source: videoSource)
+                        CommentView(comment: comment, videoID: videoID, source: videoSource, showAvatar: showAvatars)
                             .onAppear {
                                 if comment.id == comments.last?.id,
                                    playerState?.commentsContinuation != nil,