Mirror the Twilio voice configuration flow: split the WhatsApp Cloud
calling-enabled toggle out of the generic Configuration tab into a
dedicated Calls tab so the surface for telephony settings is consistent
across providers.
- Added WhatsappCallingPage.vue with the toggle, business phone display,
and a how-it-works blurb (no extra credentials needed since the
embedded-signup token already grants the call scopes).
- Settings.vue: register the page and surface a Calls tab on
WhatsApp Cloud + embedded-signup inboxes.
- ConfigurationPage.vue: drop the inline calling-enabled section, the
watcher that auto-saved on every toggle flip, and the now-orphan
updateWhatsAppCallingEnabled method.
- en/inboxMgmt.json: TABS.CALLS label + WHATSAPP_CALLING.* strings.