fix(WEB): 견적 저장 시 is_final 플래그 추가

- 임시저장: status='draft', is_final=false (최초작성)
- 최종저장: status='finalized', is_final=true (최종확정)

src/components/quotes/types.ts

@@ -841,6 +841,7 @@ export function transformV2ToApi(
     unit_symbol: '개소',
     total_amount: grandTotal,
     status: data.status === 'final' ? 'finalized' : 'draft',
+    is_final: data.status === 'final',
     calculation_inputs: calculationInputs,
     items: items,
   };