chore: Enable flexible whatsapp onboarding (Manual + Embedded Signup) options (#12344)

We recently introduced the WhatsApp Embedded Signup flow in Chatwoot to
simplify onboarding. However, we discovered two important limitations:
Some customers’ numbers are already linked to an Embedded Signup, which
blocks re-use. Tech providers cannot onboard their own numbers via
Embedded Signup.
As a result, we need to support both Manual and Embedded Signup flows to
cover all scenarios.

### Problem

- Current UI only offers the Embedded Signup option.
- Customers who need to reuse existing numbers (already connected to
WABA) or tech providers testing their own numbers get stuck.
- Manual flow exists but is no longer exposed in the UX

**Current Embedded Signup screen**
<img width="2564" height="1250" alt="CleanShot 2025-08-21 at 21 58
07@2x"
src="https://github.com/user-attachments/assets/c3de4cf1-cae6-4a0e-aa9c-5fa4e2249c0e"
/>

**Current Manual Setup screen**
<img width="2568" height="1422" alt="CleanShot 2025-08-21 at 22 00
25@2x"
src="https://github.com/user-attachments/assets/96408f97-3ffe-42d1-9019-a511e808f5ac"
/>


###  Solution

- Design a dual-path UX in the Create WhatsApp Inbox step that:
- Offers Embedded Signup (default/recommended) for new numbers and
businesses.
- Offers Manual Setup for advanced users, existing linked numbers, and
tech providers.

<img width="2030" height="1376" alt="CleanShot 2025-09-01 at 14 13
16@2x"
src="https://github.com/user-attachments/assets/6f17e5a2-a2fd-40fb-826a-c9ee778be795"
/>

---------

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

app/javascript/dashboard/i18n/locale/en/inboxMgmt.json

@@ -272,8 +272,8 @@
         },
         "SUBMIT_BUTTON": "Create WhatsApp Channel",
         "EMBEDDED_SIGNUP": {
-          "TITLE": "Quick Setup with Meta",
-          "DESC": "You will be redirected to Meta to log into your WhatsApp Business account. Having admin access will help make the setup smooth and easy.",
+          "TITLE": "Quick setup with Meta",
+          "DESC": "Use the WhatsApp Embedded Signup flow to quickly connect new numbers. You will be redirected to Meta to log into your WhatsApp Business account. Having admin access will help make the setup smooth and easy.",
           "BENEFITS": {
             "TITLE": "Benefits of Embedded Signup:",
             "EASY_SETUP": "No manual configuration required",
@@ -281,9 +281,8 @@
             "AUTO_CONFIG": "Automatic webhook and phone number configuration"
           },
           "LEARN_MORE": {
-            "TEXT": "To learn more about integrated signup, pricing, and limitations, visit",
-            "LINK_TEXT": "this link.",
-            "LINK_URL": "https://developers.facebook.com/docs/whatsapp/embedded-signup/custom-flows/onboarding-business-app-users#limitations"
+            "TEXT": "To learn more about integrated signup, pricing, and limitations, visit {link}.",
+            "LINK_TEXT": "this link"
           },
           "SUBMIT_BUTTON": "Connect with WhatsApp Business",
           "AUTH_PROCESSING": "Authenticating with Meta",
@@ -296,7 +295,9 @@
           "INVALID_BUSINESS_DATA": "Invalid business data received from Facebook. Please try again.",
           "SIGNUP_ERROR": "Signup error occurred",
           "AUTH_NOT_COMPLETED": "Authentication not completed. Please restart the process.",
-          "SUCCESS_FALLBACK": "WhatsApp Business Account has been successfully configured"
+          "SUCCESS_FALLBACK": "WhatsApp Business Account has been successfully configured",
+          "MANUAL_FALLBACK": "If your number is already connected to the WhatsApp Business Platform (API), or if you’re a tech provider onboarding your own number, please use the {link} flow",
+          "MANUAL_LINK_TEXT": "manual setup flow"
         },
         "API": {
           "ERROR_MESSAGE": "We were not able to save the WhatsApp channel"