feat: Replace caip-x with caip-348 (#53)

Replace `caip-x` with `caip-348`

See: ChainAgnostic/CAIPs#348
See: MetaMask/metamask-extension#32070

Author: jiexi

src/App.tsx

@@ -160,7 +160,10 @@ function App() {
   const handleWalletAnnounce = useCallback(
     (ev: Event) => {
       const customEvent = ev as CustomEvent;
-      const { extensionId: announcedId, rdns } = customEvent.detail.params;
+      const { targets, rdns } = customEvent.detail.params;
+      const announcedId = targets?.find(
+        (target: { type: string; value: string }) => target.type === 'caip-348',
+      )?.value;
       const newExtensionId =
         rdns === 'io.metamask.flask' && !announcedId
           ? WINDOW_POST_MESSAGE_ID

src/sdk/providers/MetaMaskMultichainExternallyConnectableProvider.ts

@@ -42,7 +42,7 @@ class MetaMaskMultichainExternallyConnectableProvider extends MetaMaskMultichain
 
     this.#port.onMessage.addListener((message) => {
       const { type, data } = message;
-      if (type !== 'caip-x') {
+      if (type !== 'caip-348') {
         return;
       }
       this._handleMessage(data);
@@ -72,7 +72,7 @@ class MetaMaskMultichainExternallyConnectableProvider extends MetaMaskMultichain
   }
 
   _sendRequest(request: JsonRpcRequest) {
-    this.#port?.postMessage({ type: 'caip-x', data: request });
+    this.#port?.postMessage({ type: 'caip-348', data: request });
   }
 }