fix: universal getSigner helper for WalletConnect + extension signing

Replace all web3FromAddress calls with getSigner() that auto-detects
walletSource and uses WC signer or extension signer accordingly.
This fixes all signing operations when connected via WalletConnect.

web/src/lib/get-signer.ts

@@ -0,0 +1,40 @@
+/**
+ * Universal signer helper - works with both browser extension and WalletConnect
+ *
+ * Usage:
+ *   const injector = await getSigner(selectedAccount.address, walletSource, api);
+ *   // injector.signer works for signAndSend, signRaw, etc.
+ */
+
+import { web3Enable, web3FromAddress } from '@pezkuwi/extension-dapp';
+import { createWCSigner, isWCConnected, validateSession } from '@/lib/walletconnect-service';
+import type { ApiPromise } from '@pezkuwi/api';
+
+type WalletSource = 'extension' | 'walletconnect' | 'native' | null;
+
+interface SignerResult {
+  signer: any; // Compatible with @pezkuwi/api Signer
+}
+
+export async function getSigner(
+  address: string,
+  walletSource: WalletSource,
+  api?: ApiPromise | null
+): Promise<SignerResult> {
+  if (walletSource === 'walletconnect') {
+    if (!isWCConnected() || !validateSession()) {
+      throw new Error('WalletConnect session expired. Please reconnect your wallet.');
+    }
+    if (!api) {
+      throw new Error('API not ready');
+    }
+    const genesisHash = api.genesisHash.toHex();
+    const wcSigner = createWCSigner(genesisHash, address);
+    return { signer: wcSigner };
+  }
+
+  // Extension or native: use web3FromAddress
+  await web3Enable('PezkuwiChain');
+  const injector = await web3FromAddress(address);
+  return injector;
+}