refactor(voice): unify inbound/outbound via orchestrator & message builder

- Add Voice::CallOrchestratorService to centralize flows
- Add Voice::CallMessageBuilder for consistent voice call messages
- Incoming/Outgoing services delegate to orchestrator; use CallStatus::Manager
- ConversationFinderService: phone optional; public call_sid lookup

feat(ui): simplify call widget + reliable incoming detection + ringtone

- Remove global widget toggling; rely on Vuex
- ActionCable: loosen created condition, backfill on updated
- Add ringtone on incoming via shared Audio helper
- Guard Twilio connect() to avoid duplicate active call errors

fix(voice): decline incoming ends call & updates status

- Reject call now completes Twilio call if in progress
- Update status via manager to no_answer with activity

app/javascript/dashboard/api/channels/voice.js

@@ -146,6 +146,19 @@ class VoiceAPI extends ApiClient {
   joinClientCall({ To }) {
     if (!this.device || !this.initialized) throw new Error('Twilio not ready');
     if (!To) throw new Error('Missing To');
+
+    // Guard: if there is already an active/connecting call, return it instead of creating a new one
+    if (this.activeConnection) {
+      return this.activeConnection;
+    }
+    if (this.device.state === 'busy') {
+      const existing = (this.device.calls || [])[0];
+      if (existing) {
+        this.activeConnection = existing;
+        return existing;
+      }
+    }
+
     const connection = this.device.connect({
       params: { To: String(To), is_agent: 'true' },
     });