Move Home shortcut style picker to its own page with live preview

Replace the inline Plain/Accent/Colorful picker in Home customization with
a navigation row that opens a dedicated page. The new page keeps the style
selector and renders a non-interactive preview of every shortcut type so
the chosen style is visible before committing.

- Add an optional styleOverride to HomeShortcutCardView so the preview can
  reflect the not-yet-saved selection.
- On macOS, navigate via navigationDestination(isPresented:) instead of a
  List-embedded NavigationLink, which otherwise stays stuck in its selected
  state after popping back and can't be reopened.

Yattee/Localizable.xcstrings

@@ -4214,6 +4214,17 @@
         }
       }
     },
+    "home.settings.shortcuts.style.preview" : {
+      "comment" : "Header for the shortcut style preview section",
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Preview"
+          }
+        }
+      }
+    },
     "home.shortcuts.style.accent" : {
       "comment" : "Accent card style option",
       "localizations" : {