fix(core): shallow-clone savedApiKeySource to avoid mutation risk

Copy the ConfigSource object before applyResolvedModelDefaults runs,
so a future refactor that mutates source objects in place won't break
the save/restore logic.

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

packages/core/src/models/modelsConfig.ts

@@ -905,6 +905,8 @@ export class ModelsConfig {
           : undefined;
         const savedApiKeySource = isUnchanged
           ? this.generationConfigSources['apiKey']
+            ? { ...this.generationConfigSources['apiKey'] }
+            : undefined
           : undefined;
 
         this.applyResolvedModelDefaults(resolved);