feat: implement Excel parser service

Implement Excel parsing module for ERP exported files following TDD principles.

Key features:
- Parse Excel files with multiple orders per file
- Extract order header information (production order, product code, etc.)
- Extract material data rows with 13 fields
- Handle empty orders gracefully
- Detect footer rows (制单人/打印人)
- Map Chinese field names to English property names
- Support field name mapping from Python reference

Implementation:
- ExcelParser class with parse() method
- DiscreteMaterialPlan and ExcelParseOptions types
- OrderHeader interface for order metadata
- Test fixtures with realistic Excel structure
- Comprehensive unit tests (3 tests, all passing)

Reference: playwrite/utils/excel_converter.py

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/main/types/excel.types.ts

@@ -0,0 +1,113 @@
+/**
+ * Excel Parser Types
+ * Defines the structure for parsed Excel data from ERP system
+ */
+
+/**
+ * Represents a discrete material plan row from Excel
+ * Based on the ERP Excel export structure
+ */
+export interface DiscreteMaterialPlan {
+  /** Order number (e.g., SC202501001) */
+  orderNumber: string;
+
+  /** Production ID from order header */
+  productionId: string;
+
+  /** Material code (材料编码) */
+  materialCode: string;
+
+  /** Material name (材料名称) */
+  materialName: string;
+
+  /** Specification (规格) */
+  specification?: string;
+
+  /** Model (型号) */
+  model?: string;
+
+  /** Drawing number (图号) */
+  drawingNumber?: string;
+
+  /** Material (物料材质) */
+  material?: string;
+
+  /** Planned quantity (计划数量) */
+  quantity: number;
+
+  /** Unit (单位) */
+  unit: string;
+
+  /** Required date (需用日期) */
+  requiredDate?: string;
+
+  /** Warehouse (发料仓库) */
+  warehouse?: string;
+
+  /** Unit usage (单位用量) */
+  unitUsage?: number;
+
+  /** Cumulative outbound quantity (累计出库数量) */
+  cumulativeOutboundQty?: number;
+
+  /** Row number in Excel file */
+  rowNumber?: number;
+}
+
+/**
+ * Options for Excel parsing
+ */
+export interface ExcelParseOptions {
+  /** Skip orders with no material data */
+  skipEmptyOrders?: boolean;
+
+  /** Skip footer rows (制单人/打印人) */
+  skipFooter?: boolean;
+
+  /** Custom field mapping */
+  fieldMapping?: Record<string, string>;
+
+  /** Verbose logging */
+  verbose?: boolean;
+}
+
+/**
+ * Order header information from Excel
+ */
+export interface OrderHeader {
+  /** Order title (离散备料计划) */
+  title?: string;
+
+  /** Production department (生产部门) */
+  productionDepartment?: string;
+
+  /** Production order (生产订单) */
+  productionOrder?: string;
+
+  /** Product code (产品编码) */
+  productCode?: string;
+
+  /** Product name (产品名称) */
+  productName?: string;
+
+  /** Product specification (产品规格) */
+  productSpecification?: string;
+
+  /** Planned quantity (计划数量) */
+  plannedQuantity?: string;
+
+  /** Unit (单位) */
+  unit?: string;
+
+  /** Required date (需用日期) */
+  requiredDate?: string;
+
+  /** Creator (制单人) */
+  creator?: string;
+
+  /** Printer (打印人) */
+  printer?: string;
+
+  /** Print date (打印日期) */
+  printDate?: string;
+}