Fix Jalali year-0 crash on /tasks from invalid target_date.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/Support/JalaliHelper.php

@@ -39,4 +39,23 @@ class JalaliHelper
 
         return $jalali ? $jalali->format($format) : $fallback;
     }
+
+    /** تاریخ میلادی امن به صورت Y-m-d */
+    public static function toGregorianDate($value, string $fallback = ''): string
+    {
+        if ($value === null || $value === '' || str_starts_with((string) $value, '0000-00-00')) {
+            return $fallback;
+        }
+
+        try {
+            $carbon = $value instanceof Carbon ? $value->copy() : Carbon::parse($value);
+            if ($carbon->year < 1000 || $carbon->year > 3000) {
+                return $fallback;
+            }
+
+            return $carbon->format('Y-m-d');
+        } catch (Throwable $e) {
+            return $fallback;
+        }
+    }
 }