fix: handle plain month number in attendance route, not just YYYY-MM

AttendanceAdmin sends ?year=YYYY&month=M (separate params), but the
route handler assumed month was always in "YYYY-MM" format. When
query.month was just "4", the split produced NaN for month and 4 for
year, causing the service to skip the month filter entirely.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/routes/admin/attendance.ts

@@ -221,10 +221,16 @@ export default async function attendanceRoutes(
       isAdmin,
       authUserId: authData.userId,
       month: query.month
-        ? Number(String(query.month).split("-")[1])
+        ? String(query.month).includes("-")
+          ? Number(String(query.month).split("-")[1])
+          : Number(query.month)
         : undefined,
       year: query.month
-        ? Number(String(query.month).split("-")[0])
+        ? String(query.month).includes("-")
+          ? Number(String(query.month).split("-")[0])
+          : query.year
+            ? Number(query.year)
+            : undefined
         : query.year
           ? Number(query.year)
           : undefined,