fix(설계 저장): 347 덧 [확정] 때 관 저장이 배수유역 다시 셈 — side.savePipes(confirm) 한 줄(승인)

- [확정] = PUT pipe-points ?recompute=true(낡았으면 지금 노선으로 배수유역부터) · [저장] = 낡음 달고 저장

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XWh5wNNycMkbwMpACz1rte

A00_Common/design/design_shared.ts

@@ -300,7 +300,7 @@ export async function saveSharedDesign(shared: DesignPageShared, confirm: boolea
         ...(side
           ? {
               pipes: async () => {
-                await side.savePipes();
+                await side.savePipes(confirm);
               },
             }
           : {}),