Simplify back to ternary now that typecast is gone

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

crates/yaak-models/guest-js/store.ts

@@ -146,10 +146,7 @@ export function duplicateModel<M extends AnyModel["model"], T extends ExtractMod
 
   // If the model has an explicit (non-empty) name, try to duplicate it with a name that doesn't conflict.
   // When the name is empty, keep it empty so the display falls back to the URL.
-  let name: string | undefined;
-  if ("name" in model) {
-    name = model.name;
-  }
+  let name = "name" in model ? model.name : undefined;
   if (name) {
     const existingModels = listModels(model.model);
     for (let i = 0; i < 100; i++) {