Browser-direct WebRTC has no rejoin path, so any call that outlives the
agent's tab becomes permanently orphaned on Meta's side. The existing
pagehide beacon only covered the active (accepted) call — extend it to
every ringing inbound too, so a hard refresh during ringing releases the
call instead of leaving Meta to time it out.
- useWhatsappCallSession: factor sendWhatsappCallBeacon(callId) out of
the active-call wrapper so any caller can post terminate for any callId
without going through the activeCallId / intentionallyClosing guard.
- useCallSession.handlePageHide: after the active-call beacon, iterate
the calls store for any ringing WhatsApp call and beacon /terminate
for each. terminate is the right endpoint because the backend records
it as 'no_answer' when the call was still ringing — accurate UX shape.