Add event-driven state sync with ETag optimization

wwwroot/js/state.js

@@ -17,6 +17,7 @@ export const state = {
     votesRendered: false,
     adminVoteStatus: null,
     adminStatusSelectActive: false,
+    stateEtag: null,
 };
 
 export function clearUserState() {
@@ -34,7 +35,9 @@ export function clearUserState() {
     state.myVotes = [];
     state.results = [];
     state.votesRendered = false;
+    state.adminVoteStatus = null;
     state.adminStatusSelectActive = false;
+    state.stateEtag = null;
     const adminCard = document.getElementById("admin-card");
     if (adminCard) adminCard.classList.add("hidden");
 }