🐛 fix(i18n): handle missing session in locale resolution

- add exception handling to manage cases where session is not in request scope

app/i18n.py

@@ -325,9 +325,13 @@ translations: Dict[str, Dict[str, str]] = {
 
 def resolve_locale(request) -> str:
     """Detect locale from session override or Accept-Language; default to de."""
+    try:
+        if "session" in request.scope:
             session_lang = request.session.get("lang")
             if session_lang in AVAILABLE_LANGUAGES:
                 return session_lang
+    except Exception:
+        pass
 
     accept = request.headers.get("accept-language", "")
     for part in accept.split(","):