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>

tests/unit/models/schema/test_inventory.py

@@ -1,16 +1,16 @@
 # tests/unit/models/schema/test_inventory.py
 """Unit tests for inventory Pydantic schemas."""
+
 import pytest
 from pydantic import ValidationError
 
 from models.schema.inventory import (
-    InventoryBase,
-    InventoryCreate,
     InventoryAdjust,
-    InventoryUpdate,
+    InventoryCreate,
+    InventoryLocationResponse,
     InventoryReserve,
     InventoryResponse,
-    InventoryLocationResponse,
+    InventoryUpdate,
     ProductInventorySummary,
 )