feat: add cancelPairingCode() and requestPairingCode() on QR clients (#22449)

* feat: add cancelPairingCode() and allow requestPairingCode()

- requestPairingCode() now exposes onCodeReceivedEvent if needed,
  so it works on clients initialized in QR mode
- Add cancelPairingCode() method to stop pairing and return to QR
- Update TypeScript definitions

* fix(auth): dynamic ADV key in getQR + structural cancelPairingCode

the getQR closure captured advSecretKey once during initialize(), but
requestpairingcode/cancelPairingCode changes the key in IndexedDB.
the stale closure key caused QR scans to fail with HMAC validation error.

fix: read key dynamically via WAWebUserPrefsMultiDevice.getADVSecretKey()
(synchronous in-memory cache) on every getQR call, matching how WhatsApp
web's internal QR component works.

cancelpairingcode now mirrors WhatsApp Web's resetLinkDeviceState:
refreshqr() restarts WebSocket for fresh refs, then
initializeqrlinking() generates a new key. QR emission happens
automatically via the existing change:ref listener.

---------

Co-authored-by: BenyFilho <168232825+BenyFilho@users.noreply.github.com>

src/Client.js

@@ -255,8 +255,6 @@ class Client extends EventEmitter {
                         window.AuthStore.Base64Tools.encodeB64(
                             registrationInfo.identityKeyPair.pubKey,
                         );
-                    const advSecretKey =
-                        await window.AuthStore.RegistrationUtils.getADVSecretKey();
                     const platform =
                         window.AuthStore.RegistrationUtils.DEVICE_PLATFORM;
                     const getQR = (ref) =>
@@ -266,10 +264,11 @@ class Client extends EventEmitter {
                         ',' +
                         identityKeyB64 +
                         ',' +
-                        advSecretKey +
+                        window
+                            .require('WAWebUserPrefsMultiDevice')
+                            .getADVSecretKey() +
                         ',' +
                         platform;
-
                     window.onQRChangedEvent(getQR(window.AuthStore.Conn.ref)); // initial qr
                     window.AuthStore.Conn.on('change:ref', (_, ref) => {
                         window.onQRChangedEvent(getQR(ref));
@@ -516,6 +515,14 @@ class Client extends EventEmitter {
         showNotification = true,
         intervalMs = 180000,
     ) {
+        await exposeFunctionIfAbsent(
+            this.pupPage,
+            'onCodeReceivedEvent',
+            async (code) => {
+                this.emit(Events.CODE_RECEIVED, code);
+                return code;
+            },
+        );
         return await this.pupPage.evaluate(
             async (phoneNumber, showNotification, intervalMs) => {
                 const getCode = async () => {
@@ -553,6 +560,22 @@ class Client extends EventEmitter {
         );
     }
 
+    /**
+     * Cancels an active pairing code session and returns to QR code mode
+     */
+    async cancelPairingCode() {
+        await this.pupPage.evaluate(async () => {
+            if (window.codeInterval) {
+                clearInterval(window.codeInterval);
+                window.codeInterval = undefined;
+            }
+            window.require('WAWebLaunchSocketUtils').refreshQR();
+            await window
+                .require('WAWebAltDeviceLinkingApi')
+                .initializeQRLinking();
+        });
+    }
+
     /**
      * Attach event listeners to WA Web
      * Private function