feat: implement password setup link for tenant registration

When admin approves tenant registration:
- Owner account created in tenant schema (in addition to admin@localhost)
- Owner assigned 'owner' role with full permissions
- Password setup email sent with secure 7-day token link
- Owner sets password via link and auto-logs into their shop

Key changes:
- Added password_setup_token fields to TenantRegistration model
- Created tenants/services.py with formatted email service
- Modified _approve_registration to create owner account
- Added password_setup_confirm view with token validation
- Created password setup template and URL route
- Added admin action to resend password setup emails

Security:
- Token expires after 7 days
- Password not transmitted in email (secure setup link)
- Owner account inactive until password set
- Admin@localhost preserved for system administrator access

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

myproject/tenants/models.py

@@ -182,6 +182,29 @@ class TenantRegistration(models.Model):
         verbose_name="Созданный тенант"
     )
 
+    # Поля для установки пароля владельцем
+    password_setup_token = models.UUIDField(
+        null=True,
+        blank=True,
+        unique=True,
+        verbose_name="Токен установки пароля",
+        help_text="UUID токен для ссылки установки пароля владельцем"
+    )
+
+    password_setup_token_created_at = models.DateTimeField(
+        null=True,
+        blank=True,
+        verbose_name="Дата создания токена",
+        help_text="Когда был создан токен установки пароля (действителен 7 дней)"
+    )
+
+    owner_notified_at = models.DateTimeField(
+        null=True,
+        blank=True,
+        verbose_name="Дата уведомления владельца",
+        help_text="Когда было отправлено письмо владельцу с ссылкой установки пароля"
+    )
+
     class Meta:
         verbose_name = "Заявка на регистрацию"
         verbose_name_plural = "Заявки на регистрацию"