feat: add automatic database import after ERP data extraction

- Add DataImportService for reading Excel and importing to database
- Extend DiscreteMaterialPlanDAO with deleteBySourceNumbers and batchInsert
- Auto-trigger database write after successful Excel merge
- Support batch delete by SourceNumber and batch insert (1000/batch)
- Update ExtractorPage UI to show import results
- Fix SQL Server query to handle undefined recordset for DELETE/INSERT

Co-Authored-By: Claude (glm-5) <noreply@anthropic.com>

tests/unit/data-importer.test.ts

@@ -0,0 +1,119 @@
+/**
+ * Unit tests for DataImportService
+ */
+
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest'
+import { DataImportService } from '../../../src/main/services/database/data-importer'
+
+// Mock the logger
+vi.mock('../../../src/main/services/logger', () => ({
+  createLogger: () => ({
+    info: vi.fn(),
+    debug: vi.fn(),
+    warn: vi.fn(),
+    error: vi.fn()
+  })
+}))
+
+// Mock the database factory
+vi.mock('../../../src/main/services/database', () => ({
+  create: vi.fn().mockResolvedValue({
+    type: 'mysql',
+    isConnected: () => true,
+    query: vi.fn().mockResolvedValue({ rows: [], rowCount: 0 }),
+    disconnect: vi.fn().mockResolvedValue(undefined)
+  })
+}))
+
+// Create mock worksheet
+const mockWorksheet = {
+  getRow: vi.fn().mockReturnValue({
+    eachCell: vi.fn((callback) => {
+      callback({ text: '工厂' }, 1)
+      callback({ text: '来源单号' }, 2)
+      callback({ text: '备料计划单号' }, 3)
+    })
+  }),
+  eachRow: vi.fn((callback) => {
+    // Skip header row (rowNumber 1)
+    // Add data rows
+    callback(
+      {
+        eachCell: vi.fn((cellCallback) => {
+          cellCallback({ text: '工厂A', value: '工厂A' }, 1)
+          cellCallback({ text: 'PO-001', value: 'PO-001' }, 2)
+          cellCallback({ text: 'PLAN-001', value: 'PLAN-001' }, 3)
+        }),
+        text: '工厂A,PO-001,PLAN-001'
+      },
+      2
+    )
+    callback(
+      {
+        eachCell: vi.fn((cellCallback) => {
+          cellCallback({ text: '工厂A', value: '工厂A' }, 1)
+          cellCallback({ text: 'PO-002', value: 'PO-002' }, 2)
+          cellCallback({ text: 'PLAN-002', value: 'PLAN-002' }, 3)
+        }),
+        text: '工厂A,PO-002,PLAN-002'
+      },
+      3
+    )
+  })
+}
+
+// Mock ExcelJS with a proper class constructor
+class MockWorkbook {
+  worksheets = [mockWorksheet]
+  xlsx = {
+    readFile: vi.fn().mockResolvedValue(undefined)
+  }
+}
+
+vi.mock('exceljs', () => {
+  return {
+    default: {
+      Workbook: MockWorkbook
+    },
+    Workbook: MockWorkbook
+  }
+})
+
+describe('DataImportService', () => {
+  let service: DataImportService
+
+  beforeEach(() => {
+    service = new DataImportService()
+    vi.clearAllMocks()
+  })
+
+  afterEach(() => {
+    vi.restoreAllMocks()
+  })
+
+  describe('importFromExcel', () => {
+    it('should return result with expected structure', async () => {
+      const result = await service.importFromExcel('/path/to/test.xlsx', 1000)
+
+      // Check that we got a result with expected structure
+      expect(result).toHaveProperty('success')
+      expect(result).toHaveProperty('recordsRead')
+      expect(result).toHaveProperty('recordsDeleted')
+      expect(result).toHaveProperty('recordsImported')
+      expect(result).toHaveProperty('uniqueSourceNumbers')
+      expect(result).toHaveProperty('errors')
+    })
+
+    it('should return records read count', async () => {
+      const result = await service.importFromExcel('/path/to/test.xlsx', 1000)
+
+      expect(result.recordsRead).toBeGreaterThanOrEqual(0)
+    })
+
+    it('should return unique source numbers count', async () => {
+      const result = await service.importFromExcel('/path/to/test.xlsx', 1000)
+
+      expect(result.uniqueSourceNumbers).toBeGreaterThanOrEqual(0)
+    })
+  })
+})