refactor: reorganize Infrastructure layer into folder structure with DI

src/GreenHome.Infrastructure/Extensions/PersianDateHelper.cs

@@ -0,0 +1,51 @@
+using System.Globalization;
+
+namespace GreenHome.Infrastructure.Extensions;
+
+/// <summary>
+/// Helper methods for Persian (Solar Hijri) date calculations.
+/// Eliminates duplicate PersianCalendar code across services.
+/// </summary>
+public static class PersianDateHelper
+{
+    private static readonly PersianCalendar PersianCalendar = new();
+
+    /// <summary>
+    /// Extracts Persian year, month, day from a DateTime and returns the formatted Persian date string (yyyy/MM/dd).
+    /// </summary>
+    public static (int Year, int Month, int Day, string PersianDate) ToPersianDate(this DateTime dateTime)
+    {
+        var localDt = dateTime.Kind == DateTimeKind.Utc ? dateTime.ToLocalTime() : dateTime;
+        var year = PersianCalendar.GetYear(localDt);
+        var month = PersianCalendar.GetMonth(localDt);
+        var day = PersianCalendar.GetDayOfMonth(localDt);
+        var persianDate = $"{year:0000}/{month:00}/{day:00}";
+        return (year, month, day, persianDate);
+    }
+
+    /// <summary>
+    /// Validates a Persian date string in yyyy/MM/dd format and extracts year, month, day.
+    /// </summary>
+    public static bool TryParsePersianDate(string? persianDate, out int year, out int month, out int day)
+    {
+        year = month = day = 0;
+
+        if (string.IsNullOrWhiteSpace(persianDate))
+            return false;
+
+        var parts = persianDate.Split('/');
+        if (parts.Length != 3)
+            return false;
+
+        if (!int.TryParse(parts[0], out year) || year < 1300 || year > 1500)
+            return false;
+
+        if (!int.TryParse(parts[1], out month) || month < 1 || month > 12)
+            return false;
+
+        if (!int.TryParse(parts[2], out day) || day < 1 || day > 31)
+            return false;
+
+        return true;
+    }
+}