feat(attendance): add SetCountsAsync to set all three age groups for a date

API/ROLAC.API/Services/IMealAttendanceService.cs

@@ -22,6 +22,13 @@ public interface IMealAttendanceService
     /// </summary>
     Task<AttendanceCountsDto> SetAsync(DateOnly date, string category, int value);
 
+    /// <summary>
+    /// Overwrites all three age-group columns for <paramref name="date"/> with absolute
+    /// values (each clamped at zero), creating the row if it does not exist, and returns
+    /// the resulting authoritative counts. Used by the back-office Sunday-attendance editor.
+    /// </summary>
+    Task<AttendanceCountsDto> SetCountsAsync(DateOnly date, int adult, int youth, int kid);
+
     /// <summary>Returns the daily counts within the inclusive date range, ordered by date (for the dashboard).</summary>
     Task<IReadOnlyList<AttendanceCountsDto>> GetRangeAsync(DateOnly from, DateOnly to);
 }

API/ROLAC.API/Services/MealAttendanceService.cs

@@ -82,6 +82,24 @@ public class MealAttendanceService : IMealAttendanceService
         return await ReadAsync(date);
     }
 
+    public async Task<AttendanceCountsDto> SetCountsAsync(DateOnly date, int adult, int youth, int kid)
+    {
+        var row = await _db.MealAttendances.FirstOrDefaultAsync(a => a.AttendanceDate == date);
+        if (row is null)
+        {
+            row = new MealAttendance { AttendanceDate = date };
+            _db.MealAttendances.Add(row);
+        }
+
+        // Counts can never be negative; clamp before writing.
+        row.AdultCount = adult < 0 ? 0 : adult;
+        row.YouthCount = youth < 0 ? 0 : youth;
+        row.KidCount   = kid   < 0 ? 0 : kid;
+
+        await _db.SaveChangesAsync();
+        return ToDto(row);
+    }
+
     public async Task<IReadOnlyList<AttendanceCountsDto>> GetRangeAsync(DateOnly from, DateOnly to)
     {
         var rows = await _db.MealAttendances.AsNoTracking()