feat: add ZeroProvider and wire into app layout

- Create components/providers/ZeroProvider.tsx with schema, queries,
  userID, context, and cacheURL configuration
- Wire ZeroProvider into app/layout.tsx wrapping GlobalLoadingProvider
  inside ReactQueryClientProvider (same position ElectricProvider had)

surfsense_web/components/providers/ZeroProvider.tsx

@@ -0,0 +1,21 @@
+"use client";
+
+import { currentUserAtom } from "@/atoms/user/user-query.atoms";
+import { queries } from "@/zero/queries";
+import { schema } from "@/zero/schema";
+import { ZeroProvider as ZeroReactProvider } from "@rocicorp/zero/react";
+import { useAtomValue } from "jotai";
+
+const cacheURL = process.env.NEXT_PUBLIC_ZERO_CACHE_URL || "http://localhost:4848";
+
+export function ZeroProvider({ children }: { children: React.ReactNode }) {
+	const { data: user } = useAtomValue(currentUserAtom);
+	const userID = user?.id ? String(user.id) : "";
+	const context = user?.id ? { userId: String(user.id) } : undefined;
+
+	return (
+		<ZeroReactProvider {...{ userID, context, cacheURL, schema, queries }}>
+			{children}
+		</ZeroReactProvider>
+	);
+}