consolidate & align collaboration socket eventing with server

src/data/localStorage.ts

@@ -36,7 +36,7 @@ export function restoreFromLocalStorage() {
       appState = JSON.parse(savedState) as AppState;
       // If we're retrieving from local storage, we should not be collaborating
       appState.isCollaborating = false;
-      appState.collaboratorCount = 0;
+      appState.collaborators = new Map();
     } catch {
       // Do nothing because appState is already null
     }