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/templates/admin/email-templates.html

@@ -361,6 +361,6 @@
 </div>
 {% endblock %}
 
-{% block scripts %}
+{% block extra_scripts %}
 <script src="{{ url_for('static', path='admin/js/email-templates.js') }}"></script>
 {% endblock %}