Add cycleTag function for tag value transitions

Implemented the cycleTag function to handle transitions between tag states ("i", "m", "s") and reset for special cases starting with "s.". This prepares the application to support dynamic tag cycling functionality.

frontend/src/App.jsx

@@ -63,6 +63,14 @@ function clearChipLS(gameId, entryId) {
   } catch {}
 }
 
+function cycleTag(tag) {
+  if (!tag) return "i";
+  if (tag === "i") return "m";
+  if (tag === "m") return "s";
+  if (typeof tag === "string" && tag.startsWith("s.")) return null;
+  return null;
+}
+
 function AdminPanel() {
   const [users, setUsers] = useState([]);