fix(ui): a page's sub-tab is remembered per browser tab, not forever

Settings, Configuration, Statistics and Users kept the last sub-tab in localStorage, so every
fresh tab opened Configuration on "Plex" as if that were its home. useTabPersistedState keeps it
in sessionStorage (account-scoped): a reload and a trip to another page keep it, a new tab starts
on the first sub-tab. The pre-selects (a Review link, the Google-link return) write the same store;
a value an older build left in localStorage is cleared on first read.

frontend/src/components/SettingsPanel.tsx

@@ -10,7 +10,7 @@ import { SCHEMES, type Scheme, type ThemePrefs } from "../lib/theme";
 import { api, HttpError, type Me } from "../lib/api";
 import { displayName, roleKey } from "../lib/api/account";
 import { notifyActionError } from "../lib/actionErrors";
-import { LS, useAccountPersistedState } from "../lib/storage";
+import { LS, useAccountPersistedState, useTabPersistedState } from "../lib/storage";
 import Avatar from "./ui/Avatar";
 import { notify, type NotifSettings } from "../lib/notifications";
 import Tooltip from "./ui/Tooltip";
@@ -68,7 +68,7 @@ export default function SettingsPanel() {
   const prefs = usePrefs();
   // "Connect YouTube" onboarding lives in WizardProvider (the Account tab's reconnect button).
   const { openWizard } = useWizard();
-  const [tabRaw, setTab] = useAccountPersistedState(LS.settingsTab, "appearance");
+  const [tabRaw, setTab] = useTabPersistedState(LS.settingsTab, "appearance");
   const panel = useTabPanel();
   // Clamp at render so a stale/removed tab id falls back to Appearance.
   const tab: TabId = TABS.some((tabItem) => tabItem.id === tabRaw)