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/utils/encryption.py

@@ -25,8 +25,6 @@ _ENCRYPTION_SALT = b"wizamart_encryption_salt_v1"
 class EncryptionError(Exception):
     """Raised when encryption or decryption fails."""
 
-    pass
-
 
 class EncryptionService:
     """