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>

models/database/letzshop.py

@@ -89,7 +89,9 @@ class LetzshopOrder(Base, TimestampMixin):
     customer_name = Column(String(255), nullable=True)
 
     # Order totals from Letzshop
-    total_amount = Column(String(50), nullable=True)  # Store as string to preserve format
+    total_amount = Column(
+        String(50), nullable=True
+    )  # Store as string to preserve format
     currency = Column(String(10), default="EUR")
 
     # Raw data storage (for debugging/auditing)