refactor: 统一 target name/description 可空语义，前端展示 fallback 到 id

- schema: name/description 允许省略或显式 null，TypeBox Union([Null, String])
- 类型: RawTargetConfig/ResolvedTargetBase/子类型/StoredTarget/TargetStatus name 改为 string | null
- checker resolve: name: t.name ?? null，不再 fallback 到 id
- 语义校验: 拒绝空字符串和纯空白 name
- SQLite: targets.name 列改为可空 TEXT
- 前端: 新增 getTargetDisplayName(target) 展示 name ?? id
- 测试: 覆盖 name/description null 全场景，查找改为按 id
- 文档: 更新 README/DEVELOPMENT 和 6 个 openspec specs

tests/web/constants/target-table-columns.test.ts

@@ -156,4 +156,28 @@ describe("createTargetTableColumns", () => {
     expect(nameColumn.sorter).toBeUndefined();
     expect(nameColumn.sortType).toBeUndefined();
   });
+
+  test("名称列 name 为 null 时显示 id", () => {
+    const nameColumn = getColumn(createTargetTableColumns(["http"]), "name");
+    const renderCell = nameColumn.cell as (params: PrimaryTableCellParams<TargetStatus>) => string;
+    const result = renderCell({
+      col: nameColumn,
+      colIndex: 1,
+      row: makeTarget({ id: "my-api", name: null }),
+      rowIndex: 0,
+    });
+    expect(result).toBe("my-api");
+  });
+
+  test("名称列 name 有值时显示 name", () => {
+    const nameColumn = getColumn(createTargetTableColumns(["http"]), "name");
+    const renderCell = nameColumn.cell as (params: PrimaryTableCellParams<TargetStatus>) => string;
+    const result = renderCell({
+      col: nameColumn,
+      colIndex: 1,
+      row: makeTarget({ id: "my-api", name: "我的 API" }),
+      rowIndex: 0,
+    });
+    expect(result).toBe("我的 API");
+  });
 });