9db298c027
Replace pandas+openpyxl with exceljs for Excel file processing. This migration enables seamless integration with the Electron main process and maintains 1:1 functional parity with the Python implementation. Key changes: - Add exceljs dependency (v4.4.0) - Implement ExcelConverter class in TypeScript with strict types - Add comprehensive unit tests (13 test cases, all passing) - Support field name mapping, order parsing, and material extraction - Handle empty data tables and file conflicts gracefully Verification: - Successfully tested with sample Excel file (99 orders, 625 records) - All unit tests passing - Output format matches Python version Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>