Fix seasonal deadline business day handling

TaxBaik.Application/Seasonal/BusinessDayCalculator.cs

@@ -0,0 +1,74 @@
+namespace TaxBaik.Application.Seasonal;
+
+public static class BusinessDayCalculator
+{
+    private static readonly HashSet<DateOnly> HolidayDates = new()
+    {
+        // 2026
+        new DateOnly(2026, 1, 1),
+        new DateOnly(2026, 2, 16),
+        new DateOnly(2026, 2, 17),
+        new DateOnly(2026, 2, 18),
+        new DateOnly(2026, 3, 1),
+        new DateOnly(2026, 3, 2),
+        new DateOnly(2026, 5, 5),
+        new DateOnly(2026, 5, 25),
+        new DateOnly(2026, 6, 6),
+        new DateOnly(2026, 8, 15),
+        new DateOnly(2026, 8, 16),
+        new DateOnly(2026, 8, 17),
+        new DateOnly(2026, 9, 24),
+        new DateOnly(2026, 9, 25),
+        new DateOnly(2026, 9, 26),
+        new DateOnly(2026, 10, 3),
+        new DateOnly(2026, 10, 4),
+        new DateOnly(2026, 10, 5),
+        new DateOnly(2026, 10, 9),
+        new DateOnly(2026, 12, 25),
+
+        // 2027
+        new DateOnly(2027, 1, 1),
+        new DateOnly(2027, 2, 6),
+        new DateOnly(2027, 2, 7),
+        new DateOnly(2027, 2, 8),
+        new DateOnly(2027, 2, 9),
+        new DateOnly(2027, 3, 1),
+        new DateOnly(2027, 3, 2),
+        new DateOnly(2027, 5, 5),
+        new DateOnly(2027, 5, 13),
+        new DateOnly(2027, 6, 6),
+        new DateOnly(2027, 8, 15),
+        new DateOnly(2027, 8, 16),
+        new DateOnly(2027, 9, 14),
+        new DateOnly(2027, 9, 15),
+        new DateOnly(2027, 9, 16),
+        new DateOnly(2027, 10, 3),
+        new DateOnly(2027, 10, 4),
+        new DateOnly(2027, 10, 9),
+        new DateOnly(2027, 10, 10),
+        new DateOnly(2027, 10, 11),
+        new DateOnly(2027, 12, 25),
+        new DateOnly(2027, 12, 26)
+    };
+
+    public static DateOnly GetEffectiveBusinessDate(DateOnly date)
+    {
+        var effectiveDate = date;
+        while (!IsBusinessDay(effectiveDate))
+        {
+            effectiveDate = effectiveDate.AddDays(1);
+        }
+
+        return effectiveDate;
+    }
+
+    public static int GetBusinessDayDiff(DateOnly date, DateOnly referenceDate)
+    {
+        var effectiveDate = GetEffectiveBusinessDate(date);
+        return effectiveDate.DayNumber - referenceDate.DayNumber;
+    }
+
+    private static bool IsBusinessDay(DateOnly date)
+        => date.DayOfWeek is not DayOfWeek.Saturday and not DayOfWeek.Sunday
+           && !HolidayDates.Contains(date);
+}

TaxBaik.Application/Services/SeasonalMarketingService.cs

@@ -15,7 +15,8 @@ public class SeasonalMarketingService
 
             if (today >= start && today <= end)
             {
-                var days = (end - today).Days;
+                var effectiveEnd = BusinessDayCalculator.GetEffectiveBusinessDate(DateOnly.FromDateTime(end)).ToDateTime(TimeOnly.MinValue);
+                var days = BusinessDayCalculator.GetBusinessDayDiff(DateOnly.FromDateTime(end), DateOnly.FromDateTime(today));
                 return new CurrentSeasonDto
                 {
                     Key = season.Key,
@@ -27,7 +28,7 @@ public class SeasonalMarketingService
                     RelatedCategorySlug = season.RelatedCategorySlug,
                     CtaText = season.CtaText,
                     DaysUntilDeadline = days,
-                    Deadline = end
+                    Deadline = effectiveEnd
                 };
             }
         }

TaxBaik.Web/Program.cs

@@ -368,7 +368,6 @@ catch (Exception ex)
 
 app.UsePathBase("/taxbaik");
 app.UseResponseCompression();
-app.UseBlazorFrameworkFiles();
 app.UseStaticFiles();
 app.UseRouting();
 app.UseRateLimiter();