feat(voice): WhatsApp Cloud Calling — UI [6] (#14346)

## Summary

Frontend for WhatsApp Cloud Calling: header / contact-panel call
buttons, ringing widget, accept/reject/hangup, mute, in-bubble audio
player + transcript, recording-on-hangup upload, mid-call reload
warning. WebRTC is browser-direct to Meta — no media server bridge.

## Closes
- https://linear.app/chatwoot/issue/PLA-150

## How to test

Requires backend support — the controller, services, model changes, and
routes ship in **#14334** (`feature/pla-150`). Merge / deploy that first
(or simultaneously); the FE alone won't function without those
endpoints.

Then on staging, for a WhatsApp Cloud + embedded-signup inbox with the
new \`Configuration → Enable voice calling\` toggle ON and webhook
registered:

1. **Outbound** — open a conversation, click the phone icon in the
conversation header (or contact panel), grant mic, your phone rings,
answer, audio both ways, hang up. Recording + transcript land in the
bubble within ~10s.
2. **Inbound** — call the business number from your phone. The
FloatingCallWidget appears bottom-right with caller name. Click accept,
audio both ways, hang up. Recording + transcript appear.
3. **Mute** — during an active WhatsApp call, click the mic icon next to
hangup. Speech stops reaching Meta until you click again.
4. **Mid-call reload guard** — try `Cmd-R` during an active call;
browser shows a confirm prompt.

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Co-authored-by: iamsivin <iamsivin@gmail.com>
Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>

app/models/channel/whatsapp.rb

@@ -44,12 +44,18 @@ class Channel::Whatsapp < ApplicationRecord
   # Meta's Calling API is only available via the embedded-signup whatsapp_cloud flow —
   # 360dialog (default provider) and manual whatsapp_cloud setups can't reach the call APIs.
   def voice_enabled?
-    provider == 'whatsapp_cloud' &&
-      provider_config['source'] == 'embedded_signup' &&
+    voice_calling_supported? &&
       provider_config['calling_enabled'].present? &&
       account.feature_enabled?('channel_voice')
   end
 
+  # Whether this inbox can do WhatsApp calling at all. Meta's Calling API is only
+  # reachable via the embedded-signup whatsapp_cloud flow, so manual whatsapp_cloud
+  # and 360dialog inboxes can't be toggled on even though calling_enabled would persist.
+  def voice_calling_supported?
+    provider == 'whatsapp_cloud' && provider_config['source'] == 'embedded_signup'
+  end
+
   def provider_service
     if provider == 'whatsapp_cloud'
       Whatsapp::Providers::WhatsappCloudService.new(whatsapp_channel: self)
@@ -58,6 +64,35 @@ class Channel::Whatsapp < ApplicationRecord
     end
   end
 
+  # Enables voice: turns calling on at Meta (idempotent), subscribes the `calls`
+  # webhook field, and sets calling_enabled. Raises on Meta failure.
+  # Saved with validate: false to skip validate_provider_config's remote credential
+  # re-check, which could spuriously fail and desync the flag from Meta.
+  def enable_voice_calling!
+    raise 'WhatsApp calling requires an embedded-signup whatsapp_cloud inbox' unless voice_calling_supported?
+    raise 'WhatsApp calling requires the channel_voice feature' unless account.feature_enabled?('channel_voice')
+
+    provider_service.update_calling_status('ENABLED')
+    webhook_setup_service.register_callback
+    self.provider_config = provider_config.merge('calling_enabled' => true)
+    save!(validate: false)
+  end
+
+  # Disables voice: unsets calling_enabled (gates the call subsystem) and drops
+  # `calls` from the webhook subscription (best-effort, so a Meta outage can't
+  # trap admins). Leaves Meta's WABA calling.status untouched.
+  def disable_voice_calling!
+    raise 'WhatsApp calling requires an embedded-signup whatsapp_cloud inbox' unless voice_calling_supported?
+
+    self.provider_config = provider_config.merge('calling_enabled' => false)
+    save!(validate: false)
+    begin
+      webhook_setup_service.register_callback(subscribed_fields: %w[messages smb_message_echoes])
+    rescue StandardError => e
+      Rails.logger.warn "[WHATSAPP CALL] disable webhook re-subscribe failed: #{e.message}"
+    end
+  end
+
   def mark_message_templates_updated
     # rubocop:disable Rails/SkipsModelValidations
     update_column(:message_templates_last_updated, Time.zone.now)
@@ -88,10 +123,11 @@ class Channel::Whatsapp < ApplicationRecord
   end
 
   def perform_webhook_setup
-    business_account_id = provider_config['business_account_id']
-    api_key = provider_config['api_key']
+    webhook_setup_service.perform
+  end
 
-    Whatsapp::WebhookSetupService.new(self, business_account_id, api_key).perform
+  def webhook_setup_service
+    Whatsapp::WebhookSetupService.new(self, provider_config['business_account_id'], provider_config['api_key'])
   end
 
   def teardown_webhooks