feat: 设置页新增模型卡片，支持为7种能力配置默认模型

tests/server/db/settings.test.ts

@@ -113,4 +113,45 @@ describe("设置数据访问层", () => {
       expect(result).toEqual({ compact: false, theme: "dark" });
     });
   });
+
+  test("updateSettings 写入 defaultModels 并读取", () => {
+    withSettingsDb((db) => {
+      const updated = updateSettings(
+        db,
+        { defaultModels: { text: "model-1", imageRecognition: null } },
+        createNoopLogger(),
+      );
+      expect(updated.defaultModels).toEqual({ text: "model-1", imageRecognition: null });
+      expect(updated.compact).toBe(false);
+      expect(updated.theme).toBe("system");
+
+      const read = getSettings(db);
+      expect(read.defaultModels).toEqual({ text: "model-1", imageRecognition: null });
+    });
+  });
+
+  test("defaultModels 与 theme/compact 合并持久化", () => {
+    withSettingsDb((db) => {
+      updateSettings(db, { theme: "dark", compact: true }, createNoopLogger());
+      const result = updateSettings(db, { defaultModels: { imageGeneration: "model-2" } }, createNoopLogger());
+      expect(result).toEqual({
+        compact: true,
+        defaultModels: { imageGeneration: "model-2" },
+        theme: "dark",
+      });
+    });
+  });
+
+  test("defaultModels 全量替换——前端负责深度合并", () => {
+    withSettingsDb((db) => {
+      updateSettings(db, { defaultModels: { text: "model-1", imageRecognition: "model-2" } }, createNoopLogger());
+      // 前端在 onChange 中负责合并 old + newField，提交完整对象
+      const result = updateSettings(
+        db,
+        { defaultModels: { text: "model-3", imageRecognition: "model-2" } },
+        createNoopLogger(),
+      );
+      expect(result.defaultModels).toEqual({ text: "model-3", imageRecognition: "model-2" });
+    });
+  });
 });