feat: Add QR codes for WhatsApp, Messenger, and Telegram on inbox finish page (#12257)

Added QR code generation for multiple messaging platforms on the inbox
finish setup page. So users can scan QR codes to instantly test their
newly created channels.

**Supported Platforms**

  - **WhatsApp**: QR code for `https://wa.me/{phone_number}`
    - Supports both WhatsApp Cloud and Twilio WhatsApp inboxes
  - **Facebook Messenger**: QR code for `https://m.me/{page_id}`
    - All Facebook page inboxes
  - **Telegram**: QR code for `https://t.me/{bot_name}`
    - All Telegram bot inboxes

**How to test the changes**
You can test these changes by navigating to this URL
`{BASE_URL}/app/accounts/{account_id}/settings/inboxes/new/{inbox_id}/finish`
and simply replacing the inbox ID with one you've already created.

**Preview**

<img width="2432" height="1474" alt="CleanShot 2025-08-21 at 15 40
59@2x"
src="https://github.com/user-attachments/assets/4226133b-9793-48ca-bf79-903b7e003ef3"
/>

---------

Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>
Co-authored-by: iamsivin <iamsivin@gmail.com>

package.json

@@ -79,6 +79,7 @@
     "md5": "^2.3.0",
     "mitt": "^3.0.1",
     "opus-recorder": "^8.0.5",
+    "qrcode": "^1.5.4",
     "posthog-js": "^1.260.2",
     "semver": "7.6.3",
     "snakecase-keys": "^8.0.1",