⚡️ perf(import): 重构导入链路并支持流式批量写入

- 后端新增流式导入流水线，避免预览和导入阶段整文件驻留内存\n- 导入执行优先复用 BatchApplier 按批提交，并在批量失败时回退单行定位错误\n- 导入进度事件兼容未预扫总行数场景，沿用预览总数稳定展示进度\n- 补充导入预览、批量回退和前端进度展示的最小回归测试

frontend/src/components/ImportPreviewModal.test.tsx

@@ -9,7 +9,11 @@ import ImportPreviewModal from "./ImportPreviewModal";
 const mocks = vi.hoisted(() => ({
   previewImportFile: vi.fn(),
   importDataWithProgress: vi.fn(),
-  eventsOn: vi.fn(() => vi.fn()),
+  progressHandler: null as ((data: any) => void) | null,
+  eventsOn: vi.fn((_event: string, handler: (data: any) => void) => {
+    mocks.progressHandler = handler;
+    return vi.fn();
+  }),
   eventsOff: vi.fn(),
   storeState: {
     connections: [
@@ -29,7 +33,8 @@ const mocks = vi.hoisted(() => ({
 }));
 
 vi.mock("../store", () => ({
-  useStore: (selector: (state: typeof mocks.storeState) => unknown) => selector(mocks.storeState),
+  useStore: (selector: (state: typeof mocks.storeState) => unknown) =>
+    selector(mocks.storeState),
 }));
 
 vi.mock("../i18n/runtime", () => ({
@@ -59,12 +64,25 @@ vi.mock("antd", async () => {
     footer?: React.ReactNode;
     open?: boolean;
     title?: React.ReactNode;
-  }) => (open ? React.createElement("section", null, title, children, footer) : null);
-  const Table = ({ columns, dataSource }: { columns?: any[]; dataSource?: any[] }) =>
+  }) =>
+    open ? React.createElement("section", null, title, children, footer) : null;
+  const Table = ({
+    columns,
+    dataSource,
+  }: {
+    columns?: any[];
+    dataSource?: any[];
+  }) =>
     React.createElement(
       "div",
       null,
-      columns?.map((column) => React.createElement("span", { key: column.key || column.dataIndex }, column.title)),
+      columns?.map((column) =>
+        React.createElement(
+          "span",
+          { key: column.key || column.dataIndex },
+          column.title,
+        ),
+      ),
       dataSource?.map((row, index) =>
         React.createElement(
           "div",
@@ -78,12 +96,24 @@ vi.mock("antd", async () => {
   return {
     Modal,
     Table,
-    Alert: ({ message, description }: { message?: React.ReactNode; description?: React.ReactNode }) =>
-      React.createElement("div", null, message, description),
-    Progress: ({ percent }: { percent: number }) => React.createElement("div", null, `${percent}%`),
-    Button: ({ children, onClick }: { children?: React.ReactNode; onClick?: () => void }) =>
-      React.createElement("button", { onClick }, children),
-    Space: ({ children }: { children?: React.ReactNode }) => React.createElement("div", null, children),
+    Alert: ({
+      message,
+      description,
+    }: {
+      message?: React.ReactNode;
+      description?: React.ReactNode;
+    }) => React.createElement("div", null, message, description),
+    Progress: ({ percent }: { percent: number }) =>
+      React.createElement("div", null, `${percent}%`),
+    Button: ({
+      children,
+      onClick,
+    }: {
+      children?: React.ReactNode;
+      onClick?: () => void;
+    }) => React.createElement("button", { onClick }, children),
+    Space: ({ children }: { children?: React.ReactNode }) =>
+      React.createElement("div", null, children),
   };
 });
 
@@ -99,7 +129,8 @@ vi.mock("@ant-design/icons", async () => {
 const textContent = (node: any): string => {
   if (node === null || node === undefined) return "";
   if (typeof node === "string" || typeof node === "number") return String(node);
-  if (Array.isArray(node)) return node.map((item) => textContent(item)).join("");
+  if (Array.isArray(node))
+    return node.map((item) => textContent(item)).join("");
   return textContent(node.children || []);
 };
 
@@ -146,7 +177,9 @@ describe("ImportPreviewModal i18n", () => {
 
     expect(renderedText).toContain("Import data preview");
     expect(renderedText).toContain("12 rows and 2 fields");
-    expect(renderedText).toContain("The first 5 rows are shown below. Start the import after confirming the data.");
+    expect(renderedText).toContain(
+      "The first 5 rows are shown below. Start the import after confirming the data.",
+    );
     expect(renderedText).toContain("Field list:");
     expect(renderedText).toContain("Data preview (first 5 rows):");
     expect(renderedText).toContain("Cancel");
@@ -156,7 +189,10 @@ describe("ImportPreviewModal i18n", () => {
   });
 
   it("does not keep migrated Chinese UI literals in ImportPreviewModal source", () => {
-    const source = readFileSync(new URL("./ImportPreviewModal.tsx", import.meta.url), "utf8");
+    const source = readFileSync(
+      new URL("./ImportPreviewModal.tsx", import.meta.url),
+      "utf8",
+    );
 
     expect(source).not.toContain("导入数据预览");
     expect(source).not.toContain("开始导入");
@@ -166,4 +202,49 @@ describe("ImportPreviewModal i18n", () => {
     expect(source).not.toContain("正在导入数据...");
     expect(source).not.toContain("错误日志：");
   });
+
+  it("keeps preview total when progress events omit total rows", async () => {
+    let resolveImport!: (value: any) => void;
+    mocks.importDataWithProgress.mockImplementation(
+      () =>
+        new Promise((resolve) => {
+          resolveImport = resolve;
+        }),
+    );
+
+    const renderer = await renderImportPreview();
+    const button = renderer.root
+      .findAllByType("button")
+      .find((node) => textContent(node.props.children) === "Start import");
+    expect(button).toBeDefined();
+
+    await act(async () => {
+      button?.props.onClick();
+      await Promise.resolve();
+    });
+
+    expect(mocks.progressHandler).toBeTypeOf("function");
+
+    await act(async () => {
+      mocks.progressHandler?.({
+        current: 3,
+        total: 0,
+        success: 3,
+        errors: 0,
+        totalRowsKnown: false,
+      });
+      await Promise.resolve();
+    });
+
+    expect(textContent(renderer.toJSON())).toContain("Processed 3 / 12 rows");
+    expect(textContent(renderer.toJSON())).toContain("25%");
+
+    await act(async () => {
+      resolveImport({
+        success: true,
+        data: { success: 3, failed: 0, total: 12, errorLogs: [] },
+      });
+      await Promise.resolve();
+    });
+  });
 });