fix: setup webhook for create and update should be done after db commit (#12176)

## Reference
https://github.com/chatwoot/chatwoot/pull/12149#issuecomment-3178108388

## Description

setup_webhook was done before the save, and hence the meta webhook
validation might fail because of a race condition where the facebook
validation is done before we saving the entry to the database.

## Type of change

Please delete options that are not relevant.

- [ ] Bug fix (non-breaking change which fixes an issue)

## How Has This Been Tested?

- New inbox creation, webhook validation
- Existing inbox update, webhook validation
- 
<img width="614" height="674" alt="image"
src="https://github.com/user-attachments/assets/be223945-deed-475a-82e5-3ae9c54a13fa"
/>


## Checklist:

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

---------

Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

app/services/whatsapp/channel_creation_service.rb

@@ -33,15 +33,14 @@ class Whatsapp::ChannelCreationService
 
   def create_channel_with_inbox
     ActiveRecord::Base.transaction do
-      channel = create_channel
+      channel = build_channel
       create_inbox(channel)
-      channel.reload
       channel
     end
   end
 
-  def create_channel
-    Channel::Whatsapp.create!(
+  def build_channel
+    Channel::Whatsapp.build(
       account: @account,
       phone_number: @phone_info[:phone_number],
       provider: 'whatsapp_cloud',

app/services/whatsapp/embedded_signup_service.rb

@@ -11,16 +11,34 @@ class Whatsapp::EmbeddedSignupService
   def perform
     validate_parameters!
 
-    # Exchange code for user access token
-    access_token = Whatsapp::TokenExchangeService.new(@code).perform
+    access_token = exchange_code_for_token
+    phone_info = fetch_phone_info(access_token)
+    validate_token_access(access_token)
 
-    # Fetch phone information
-    phone_info = Whatsapp::PhoneInfoService.new(@waba_id, @phone_number_id, access_token).perform
+    channel = create_or_reauthorize_channel(access_token, phone_info)
+    channel.setup_webhooks
+    channel
 
-    # Validate token has access to the WABA
+  rescue StandardError => e
+    Rails.logger.error("[WHATSAPP] Embedded signup failed: #{e.message}")
+    raise e
+  end
+
+  private
+
+  def exchange_code_for_token
+    Whatsapp::TokenExchangeService.new(@code).perform
+  end
+
+  def fetch_phone_info(access_token)
+    Whatsapp::PhoneInfoService.new(@waba_id, @phone_number_id, access_token).perform
+  end
+
+  def validate_token_access(access_token)
     Whatsapp::TokenValidationService.new(access_token, @waba_id).perform
+  end
 
-    # Reauthorization flow if inbox_id is present
+  def create_or_reauthorize_channel(access_token, phone_info)
     if @inbox_id.present?
       Whatsapp::ReauthorizationService.new(
         account: @account,
@@ -29,17 +47,11 @@ class Whatsapp::EmbeddedSignupService
         business_id: @business_id
       ).perform(access_token, phone_info)
     else
-      # Create channel for new authorization
       waba_info = { waba_id: @waba_id, business_name: phone_info[:business_name] }
       Whatsapp::ChannelCreationService.new(@account, waba_info, phone_info, access_token).perform
     end
-  rescue StandardError => e
-    Rails.logger.error("[WHATSAPP] Embedded signup failed: #{e.message}")
-    raise e
   end
 
-  private
-
   def validate_parameters!
     missing_params = []
     missing_params << 'code' if @code.blank?