fix: keep birthdays and show Shamsi dates

Imported customers keep their birthday, and assistant text plus remaining calendars use the Jalali date.

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

apps/api/prisma/migrations/20261013140000_person_lead_birth_date/migration.sql

@@ -0,0 +1,5 @@
+-- AlterTable
+ALTER TABLE "Person" ADD COLUMN "birthDate" TIMESTAMP(3);
+
+-- AlterTable
+ALTER TABLE "Lead" ADD COLUMN "birthDate" TIMESTAMP(3);

apps/api/prisma/schema.prisma

@@ -498,6 +498,8 @@ model Person {
   website                 String?
   /// پیج اینستاگرام
   instagram               String?
+  /// تاریخ تولد
+  birthDate               DateTime?
   /// نام معرف
   referrer                String?
   /// لیست آدرس‌ها (JSON array of strings)
@@ -2391,6 +2393,8 @@ model Lead {
   region            String?
   /// پیج اینستاگرام
   instagram         String?
+  /// تاریخ تولد
+  birthDate         DateTime?
   /// لیست آدرس‌ها (JSON array of strings)
   addresses         Json            @default("[]")
   /// صنف