fix: resolve all architecture validation errors (62 -> 0)

Major refactoring to achieve zero architecture violations:

API Layer:
- vendor/settings.py: Move validation to Pydantic field validators
  (tax rate, delivery method, boost sort, preorder days, languages, locales)
- admin/email_templates.py: Add Pydantic response models
  (TemplateListResponse, CategoriesResponse)
- shop/auth.py: Move password reset logic to CustomerService

Service Layer:
- customer_service.py: Add password reset methods
  (get_customer_for_password_reset, validate_and_reset_password)

Exception Layer:
- customer.py: Add InvalidPasswordResetTokenException,
  PasswordTooShortException

Frontend:
- admin/email-templates.js: Use apiClient, Utils.showToast()
- vendor/email-templates.js: Use apiClient, parent init pattern

Templates:
- admin/email-templates.html: Fix block name to extra_scripts
- shop/base.html: Add language default filter

Tooling:
- validate_architecture.py: Fix LANG-001 false positive for
  SUPPORTED_LANGUAGES and SUPPORTED_LOCALES blocks

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/exceptions/customer.py

@@ -91,3 +91,26 @@ class CustomerAuthorizationException(BusinessLogicException):
             error_code="CUSTOMER_NOT_AUTHORIZED",
             details={"customer_email": customer_email, "operation": operation},
         )
+
+
+class InvalidPasswordResetTokenException(ValidationException):
+    """Raised when password reset token is invalid or expired."""
+
+    def __init__(self):
+        super().__init__(
+            message="Invalid or expired password reset link. Please request a new one.",
+            field="reset_token",
+        )
+        self.error_code = "INVALID_RESET_TOKEN"
+
+
+class PasswordTooShortException(ValidationException):
+    """Raised when password doesn't meet minimum length requirement."""
+
+    def __init__(self, min_length: int = 8):
+        super().__init__(
+            message=f"Password must be at least {min_length} characters long",
+            field="password",
+            details={"min_length": min_length},
+        )
+        self.error_code = "PASSWORD_TOO_SHORT"