Add List/Grid layout option for Home sections

Introduces a "Display sections as" picker in Home settings with List and
Grid modes. Grid renders each section as a horizontal shelf of video
cards, defaulting to Grid on tvOS and List on iOS/macOS. Per-platform
defaults are preserved via a platform-specific settings key.

On tvOS the shelf is a focus section so swiping up/down between rows of
different lengths works without getting stuck at the end of a row.

Yattee/Localizable.xcstrings

@@ -4025,6 +4025,17 @@
         }
       }
     },
+    "home.settings.sections.layout" : {
+      "comment" : "Label for sections layout picker in library settings",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Display sections as"
+          }
+        }
+      }
+    },
     "home.settings.shortcuts.layout" : {
       "comment" : "Label for shortcuts layout picker in library settings",
       "localizations" : {
@@ -4036,6 +4047,28 @@
         }
       }
     },
+    "home.sections.layout.grid" : {
+      "comment" : "Grid layout option for library sections",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Grid"
+          }
+        }
+      }
+    },
+    "home.sections.layout.list" : {
+      "comment" : "List layout option for library sections",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "List"
+          }
+        }
+      }
+    },
     "home.settings.sourceDisabled" : {
 
     },