fix: use single quotes for x-data attributes with tojson

The Jinja |tojson filter outputs JSON with double quotes. When used
inside a double-quoted HTML attribute, these quotes break the attribute
parsing causing "expected expression, got '}'" errors.

Solution: Use single quotes for x-data attributes so JSON double quotes
don't conflict:
  <div x-data='languageSelector("fr", {{ langs|tojson }})'>

Updated:
- language_selector.html macro (all 3 variants)
- shop/base.html language selector
- LANG-002 and LANG-003 architecture rules documentation
- Validator to detect double-quoted x-data with tojson

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

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

scripts/validate_architecture.py

@@ -2809,22 +2809,22 @@ class ArchitectureValidator:
                                     line_number=i,
                                     message="Complex language selector should use languageSelector() function",
                                     context=line.strip()[:80],
-                                    suggestion="Use: x-data=\"languageSelector('{{ lang }}', {{ langs|tojson }})\"",
+                                    suggestion="Use: x-data='languageSelector(\"{{ lang }}\", {{ langs|tojson }})'",
                                 )
 
-                    # LANG-003: Check for tojson|safe in HTML attributes (breaks parsing)
-                    # In x-data attributes, |tojson WITHOUT |safe is correct (quotes become ")
-                    # In <script> blocks, |tojson|safe is correct (raw JSON is valid)
-                    if "|tojson|safe" in line and "x-data=" in line:
+                    # LANG-003: Check for double-quoted x-data with tojson (breaks parsing)
+                    # Double quotes + tojson outputs raw JSON double quotes that break HTML
+                    # Use single quotes for x-data when using tojson
+                    if 'x-data="' in line and "|tojson" in line:
                         self._add_violation(
                             rule_id="LANG-003",
-                            rule_name="Do not use tojson|safe in HTML attributes",
+                            rule_name="Use single quotes for x-data with tojson",
                             severity=Severity.ERROR,
                             file_path=file_path,
                             line_number=i,
-                            message="|tojson|safe in x-data breaks HTML attribute parsing",
+                            message="Double-quoted x-data with |tojson breaks HTML (JSON has double quotes)",
                             context=line.strip()[:80],
-                            suggestion="Remove |safe: {{ variable|tojson }} - quotes become &quot; which browsers decode",
+                            suggestion="Use single quotes: x-data='func({{ data|tojson }})'",
                         )
             except Exception:
                 pass  # Skip files that can't be read