chore(voice): drop debug toasts; appease rubocop on inbox jbuilder

- Remove the [debug] useAlert breadcrumbs that surfaced the accept-call
  silent-fail (the !conversation guard). The actual fix from
  6ed9500792 stays.
- Rubocop Style/IfUnlessModifier on the WhatsApp voice_enabled jbuilder
  block — convert to modifier form.

app/javascript/dashboard/composables/useCallSession.js

@@ -9,7 +9,6 @@ import {
   cleanupWhatsappSession,
 } from 'dashboard/composables/useWhatsappCallSession';
 import { handleVoiceCallCreated } from 'dashboard/helper/voice';
-import { useAlert } from 'dashboard/composables';
 import Timer from 'dashboard/helper/Timer';
 
 const isWhatsappCall = call => call?.provider === 'whatsapp';
@@ -123,34 +122,22 @@ export function useCallSession() {
   };
 
   const joinCall = async ({ conversationId, inboxId, callSid }) => {
-    useAlert(`[debug] joinCall: callSid=${callSid} inboxId=${inboxId}`);
-    if (isJoining.value) {
-      useAlert('[debug] joinCall bailed: isJoining flag stuck');
-      return null;
-    }
+    if (isJoining.value) return null;
 
     isJoining.value = true;
     try {
       const call = findCall(callSid);
-      useAlert(
-        `[debug] found call? provider=${call?.provider} callId=${call?.callId} hasSdpOffer=${Boolean(call?.sdpOffer)}`
-      );
       if (isWhatsappCall(call)) {
-        useAlert('[debug] taking WhatsApp accept path');
         await whatsappSession.acceptIncomingCall({
           callId: call.callId,
           sdpOffer: call.sdpOffer,
           iceServers: call.iceServers,
         });
-        useAlert('[debug] /accept POST succeeded');
         callsStore.setCallActive(callSid);
         durationTimer.start();
         return { callId: call.callId };
       }
 
-      useAlert(
-        `[debug] taking Twilio path — provider mismatch: ${call?.provider}`
-      );
       const device = await TwilioVoiceClient.initializeDevice(inboxId);
       if (!device) return null;
 
@@ -171,7 +158,6 @@ export function useCallSession() {
 
       return { conferenceSid: joinResponse?.conference_sid };
     } catch (error) {
-      useAlert(`[debug] joinCall threw: ${error?.message || error}`);
       // eslint-disable-next-line no-console
       console.error('Failed to join call:', error);
       // Tear down any half-built WebRTC state so the user's next click starts