Add unified page-based details panel on existing layouts

Phase 1 of the player panels redesign:

- New PanelSettings model (pages, regions, layout mode, default
  visibility) stored as an optional field on PlayerControlsLayout with
  an effectivePanelSettings accessor; lenient Codable so future page
  types and settings payloads never corrupt saved presets.
- New Views/Player/Panels content engine: PlayerPanelContentView
  renders a page bar plus the selected page (info, comments, related,
  chapters, queue, tracks), with runtime hiding of empty pages.
- PortraitDetailsPanel and FloatingDetailsPanel now host the shared
  content instead of their duplicated info bodies; drag machinery,
  pills, and fades are untouched.
- Comments list extracted into CommentsListContent shared by the
  overlay and the comments page; comments pill routes to the comments
  page (expanding the portrait panel) when the page is enabled, and
  falls back to the overlay when it is not.
- Tracks page embeds QualitySelectorView via a new isEmbedded mode.
- Deleted the unused video info bodies in ExpandedPlayerSheet+VideoInfo
  and the dead PlayerInfoTab model.

Yattee/Localizable.xcstrings

@@ -7434,6 +7434,50 @@
         }
       }
     },
+    "panel.page.info" : {
+      "comment" : "Details panel page name",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Info"
+          }
+        }
+      }
+    },
+    "panel.page.queue" : {
+      "comment" : "Details panel page name",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Queue"
+          }
+        }
+      }
+    },
+    "panel.page.related" : {
+      "comment" : "Details panel page name",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Related"
+          }
+        }
+      }
+    },
+    "panel.page.tracks" : {
+      "comment" : "Details panel page name",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Tracks"
+          }
+        }
+      }
+    },
     "peertube.explore.added" : {
       "localizations" : {
         "en" : {