fix(frontend): resolve React hydration error #418 and WalletConnect URL mismatch

- wagmi config: add ssr: true so wallet reconnect defers until after hydration.
  Prevents React error #418 (server renders "Connect Wallet", client hydrated with
  connected address — DOM mismatch crashed the app).
- WalletConnect metadata.url: nexucore.xyz → www.nexucore.xyz to match actual
  page origin. Mismatched origin causes WalletConnect to silently reject connections.

Author: arhantbarmate

frontend/src/lib/wagmi.ts

@@ -15,15 +15,16 @@ export const polkadotHubTestnet = {
 
 export const config = createConfig({
   chains: [polkadotHubTestnet],
+  ssr: true, // defer wallet reconnect until after hydration — prevents React error #418
   connectors: [
     injected(),
     walletConnect({
       projectId: "327cde52817024c462716ebabea9cb1e",
       metadata: {
         name: "DotLend",
         description: "Non-custodial money market on Polkadot Hub",
-        url: "https://nexucore.xyz",
-        icons: ["https://nexucore.xyz/favicon.ico"],
+        url: "https://www.nexucore.xyz",
+        icons: ["https://www.nexucore.xyz/favicon.ico"],
       },
     }),
   ],