fix(voice): terminate ringing WhatsApp calls on page close

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.

app/javascript/dashboard/composables/useWhatsappCallSession.js

@@ -329,15 +329,26 @@ export const isWhatsappCallMuted = () => {
   return !tracks[0].enabled;
 };
 
-// Best-effort terminate when the tab actually closes after the beforeunload prompt.
-export const sendWhatsappTerminateBeacon = () => {
-  if (!activeCallId || intentionallyClosing) return;
+// Best-effort terminate beacon for any WhatsApp call — the backend's terminate
+// endpoint handles both ringing and in_progress states (rejecting via terminate
+// records 'no_answer' which is the right shape for "agent left the page").
+// Browser-direct WebRTC has no rejoin path, so the only sensible thing on
+// page close is to release the call on Meta's side.
+export const sendWhatsappCallBeacon = callId => {
+  if (!callId) return;
   const accountId = window.location.pathname.split('/')[3];
   if (!accountId) return;
-  const url = `/api/v1/accounts/${accountId}/whatsapp_calls/${activeCallId}/terminate`;
+  const url = `/api/v1/accounts/${accountId}/whatsapp_calls/${callId}/terminate`;
   try {
     navigator.sendBeacon(url);
   } catch (_) {
     /* noop */
   }
 };
+
+// Backward-compat wrapper for the active-call case — guarded by
+// intentionallyClosing so we don't double-terminate after an explicit hangup.
+export const sendWhatsappTerminateBeacon = () => {
+  if (!activeCallId || intentionallyClosing) return;
+  sendWhatsappCallBeacon(activeCallId);
+};