refactor: 重构解决方案相关Mapper

- 空值处理与类型控制：为关系型字段添加空值处理与类型控制逻辑
- 目录结构调整：分离SolutionList与Solution相关的Mapper为不同的文件

server/mappers/solutionListMapper.ts

@@ -0,0 +1,58 @@
+import { isObject } from '../../server/utils/object';
+
+/**
+ * 将 Directus 返回的 SolutionType 数据转换为 SolutionTypeView 视图模型
+ *
+ * @param raw: 原始的 SolutionType 数据
+ * @returns 转换后的 SolutionTypeView 对象
+ *
+ * ---
+ *
+ *  @example
+ *  const view = toSolutionTypeView(rawSolutionType);
+ */
+export function toSolutionTypeView(
+  raw: SolutionType | string | null
+): SolutionTypeView {
+  if (typeof raw === 'string' || raw === null) {
+    return {
+      id: '-1',
+      name: 'uncategory',
+      sort: 999,
+    } satisfies SolutionTypeView;
+  }
+  const trans = raw?.translations?.[0];
+
+  return {
+    id: raw.id.toString(),
+    name: trans?.name ?? '',
+    sort: raw?.sort ?? 999,
+  };
+}
+
+/**
+ * 将 Directus 返回的 Solution 数据转换为 SolutionListView 视图模型
+ *
+ * @param raw: 原始的 Solution 数据
+ * @returns 转换后的 SolutionListView 对象
+ *
+ * ---
+ *
+ * @example
+ * const view = toSolutionListView(rawSolution);
+ */
+export function toSolutionListView(raw: Solution): SolutionListView {
+  const trans = raw.translations?.[0];
+
+  const type = toSolutionTypeView(raw.type ?? null);
+
+  const cover = isObject<DirectusFile>(raw.cover) ? (raw?.cover.id ?? '') : '';
+
+  return {
+    id: raw.id.toString(),
+    title: trans?.title ?? '',
+    summary: trans?.summary ?? '',
+    solution_type: type,
+    cover: cover,
+  };
+}