Count CME holiday sessions as one combined trading day when the type opts in

Account types with the catalog's new combineCmeHolidays flag are read
through a combined-day view: holiday-session P&L entries fold into the
next full trading day (computed from the federal-holiday rules, so any
year works), the day count matches how the firm records it (Apex: Sun/
Mon/Tue around a Monday holiday is ONE day), and on the later sessions
of the stretch the earlier sessions' booked P&L carries into realized —
so day targets, already-traded gates, target-hit status and the panel's
day P&L all treat the stretch as a single day. Off by default; older
masters that don't send the flag behave exactly as before.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app/api/firms/route.ts

@@ -37,6 +37,7 @@ export async function GET() {
                     maxPositionSize: a.maxPositionSize,
                     targetSameEquity: a.targetSameEquity,
                     splitEnabled: a.splitEnabled,
+                    combineCmeHolidays: a.combineCmeHolidays,
                     withdrawalStages: a.withdrawalStages,
                 })),
                 catalogUpdatedAt: firm.updatedAt,