Fix LLM validation and dashboard health hot paths

backend/src/services/profile_service.py

@@ -117,6 +117,33 @@ class ProfileService:
             )
     # [/DEF:get_my_preference:Function]
 
+    # [DEF:get_dashboard_filter_binding:Function]
+    # @PURPOSE: Return only dashboard-filter fields required by dashboards listing hot path.
+    # @PRE: current_user is authenticated.
+    # @POST: Returns normalized username and profile-default filter toggles without security summary expansion.
+    def get_dashboard_filter_binding(self, current_user: User) -> dict:
+        with belief_scope("ProfileService.get_dashboard_filter_binding", f"user_id={current_user.id}"):
+            preference = self._get_preference_row(current_user.id)
+            if preference is None:
+                return {
+                    "superset_username": None,
+                    "superset_username_normalized": None,
+                    "show_only_my_dashboards": False,
+                    "show_only_slug_dashboards": True,
+                }
+
+            return {
+                "superset_username": self._sanitize_username(preference.superset_username),
+                "superset_username_normalized": self._normalize_username(preference.superset_username),
+                "show_only_my_dashboards": bool(preference.show_only_my_dashboards),
+                "show_only_slug_dashboards": bool(
+                    preference.show_only_slug_dashboards
+                    if preference.show_only_slug_dashboards is not None
+                    else True
+                ),
+            }
+    # [/DEF:get_dashboard_filter_binding:Function]
+
     # [DEF:update_my_preference:Function]
     # @PURPOSE: Validate and persist current user's profile preference in self-scoped mode.
     # @PRE: current_user is authenticated and payload is provided.