Add multisig pending-operations UI, fix broken multisig address calc, new signing portal

- calculateMultisigAddress was completely broken (hex-decoded an SS58 string
  and never hashed the preimage) - fixed via @pezkuwi/util-crypto's real
  encodeMultiAddress/createKeyMulti, verified against the actual known
  multisig address on-chain.
- ReservesDashboardPage had stale Noter/Berdevk addresses that don't match
  the real signers - centralized as BRIDGE_MULTISIG_SPECIFIC_ADDRESSES.
- USDTBridge withdrawal called assets.burn directly as a single-signer
  extrinsic (always fails - only the multisig is Admin) while only
  checking status.isFinalized (a failed dispatch is still finalized, so it
  silently did nothing) - replaced with the correct transfer-to-custody
  flow the relayer actually watches for.
- New MultisigOperationsPage (/multisig/pending) lists pending calls from
  real Multisig.Multisigs storage and lets any of the 5 signers
  approve/reject with their own wallet extension.
- New standalone sign/ app (deployed separately at
  pezbridge-sign.pex.mom) - a dedicated, gated signing portal for the same
  operations, so signing isn't dependent on this app alone.

web/src/pages/MultisigOperationsPage.tsx

@@ -0,0 +1,30 @@
+import React from 'react';
+import { useNavigate } from 'react-router-dom';
+import { useTranslation } from 'react-i18next';
+import { ArrowLeft } from 'lucide-react';
+import { MultisigOperations } from '@/components/MultisigOperations';
+
+const MultisigOperationsPage = () => {
+  const navigate = useNavigate();
+  const { t } = useTranslation();
+
+  return (
+    <div className="min-h-screen bg-gray-950 pt-24 pb-12">
+      <div className="container mx-auto px-4 py-8 relative max-w-3xl">
+        <button
+          onClick={() => navigate('/wallet')}
+          className="absolute top-4 left-4 text-gray-400 hover:text-white transition-colors flex items-center gap-2"
+        >
+          <ArrowLeft className="w-5 h-5" />
+          <span>{t('multisigOps.backToWallet')}</span>
+        </button>
+
+        <div className="pt-16">
+          <MultisigOperations />
+        </div>
+      </div>
+    </div>
+  );
+};
+
+export default MultisigOperationsPage;