Credit purchase listing (multi-row header: Supplier/Weight/Price/Inc.Rate/Subsidy/Deductions group/Net Pay/Debit Bal C/F)
Sprint 0 prototype 完整布局 + Compumatrix 风格保留
Sprint 1: 接 Supabase + 真数据 + auth + RLS
Sprint 2: PDF/Excel I/O + 完整业务逻辑