fix: add AuthorizeCall signed extension for PezkuwiChain transactions

PezkuwiChain requires AuthorizeCall as the first signed extension in
all transactions. Without this extension properly configured, transactions
fail with "bad signature" errors.

Added signedExtensions configuration to:
- ApiPromise.create() in Api.tsx
- getApi() in StakingAsync.tsx
- Test API creation functions

This fix enables proper transaction signing for PezkuwiChain mainnet
and teyrchains (Asset Hub, People Chain).

packages/react-api/src/Api.tsx

@@ -280,10 +280,19 @@ async function createApi (apiUrl: string, signer: ApiSigner, isLocalFork: boolea
       provider = new WsProvider(apiUrl);
     }
 
+    // PezkuwiChain requires AuthorizeCall signed extension for all transactions
+    const pezkuwiSignedExtensions = {
+      AuthorizeCall: {
+        extrinsic: {},
+        payload: {}
+      }
+    };
+
     statics.api = new ApiPromise({
       provider,
       registry: statics.registry,
       signer,
+      signedExtensions: pezkuwiSignedExtensions,
       types,
       typesBundle
     });