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/api/v1/admin/email_templates.py

@@ -58,12 +58,37 @@ class TestEmailRequest(BaseModel):
     variables: dict[str, Any] = {}
 
 
+class TemplateListItem(BaseModel):
+    """Schema for a template in the list."""
+
+    code: str
+    name: str
+    description: str
+    category: str
+    available_languages: list[str]
+
+    class Config:
+        from_attributes = True
+
+
+class TemplateListResponse(BaseModel):
+    """Response schema for listing templates."""
+
+    templates: list[TemplateListItem]
+
+
+class CategoriesResponse(BaseModel):
+    """Response schema for template categories."""
+
+    categories: list[str]
+
+
 # =============================================================================
 # ENDPOINTS
 # =============================================================================
 
 
-@router.get("")
+@router.get("", response_model=TemplateListResponse)
 def list_templates(
     current_user: User = Depends(get_current_admin_api),
     db: Session = Depends(get_db),
@@ -74,17 +99,17 @@ def list_templates(
     Returns templates grouped by code with available languages.
     """
     service = EmailTemplateService(db)
-    return {"templates": service.list_platform_templates()}
+    return TemplateListResponse(templates=service.list_platform_templates())
 
 
-@router.get("/categories")
+@router.get("/categories", response_model=CategoriesResponse)
 def get_categories(
     current_user: User = Depends(get_current_admin_api),
     db: Session = Depends(get_db),
 ):
     """Get list of email template categories."""
     service = EmailTemplateService(db)
-    return {"categories": service.get_template_categories()}
+    return CategoriesResponse(categories=service.get_template_categories())
 
 
 @router.get("/{code}")