fix: correct tojson|safe usage in templates and update validator

- Remove |safe from |tojson in HTML attributes (x-data) - quotes must
  become " for browsers to parse correctly
- Update LANG-002 and LANG-003 architecture rules to document correct
  |tojson usage patterns:
  - HTML attributes: |tojson (no |safe)
  - Script blocks: |tojson|safe
- Fix validator to warn when |tojson|safe is used in x-data (breaks
  HTML attribute parsing)
- Improve code quality across services, APIs, and tests

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

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

app/exceptions/__init__.py

@@ -46,6 +46,16 @@ from .base import (
     WizamartException,
 )
 
+# Cart exceptions
+from .cart import (
+    CartItemNotFoundException,
+    CartValidationException,
+    EmptyCartException,
+    InsufficientInventoryForCartException,
+    InvalidCartQuantityException,
+    ProductNotAvailableForCartException,
+)
+
 # Code quality exceptions
 from .code_quality import (
     InvalidViolationStatusException,
@@ -57,16 +67,6 @@ from .code_quality import (
     ViolationOperationException,
 )
 
-# Cart exceptions
-from .cart import (
-    CartItemNotFoundException,
-    CartValidationException,
-    EmptyCartException,
-    InsufficientInventoryForCartException,
-    InvalidCartQuantityException,
-    ProductNotAvailableForCartException,
-)
-
 # Company exceptions
 from .company import (
     CompanyAlreadyExistsException,