feat: Voice Channel (#11602)

Enables agents to initiate outbound calls and receive incoming calls
directly from the Chatwoot dashboard, with Twilio as the initial
provider.

Fixes:  #11481 

> This is an integration branch to ensure features works well and might
be often broken on down merges, we will be extracting the
functionalities via smaller PRs into develop

- [x] https://github.com/chatwoot/chatwoot/pull/11775
- [x] https://github.com/chatwoot/chatwoot/pull/12218
- [x] https://github.com/chatwoot/chatwoot/pull/12243
- [x] https://github.com/chatwoot/chatwoot/pull/12268
- [x] https://github.com/chatwoot/chatwoot/pull/12361
- [x]  https://github.com/chatwoot/chatwoot/pull/12782
- [x] #13064
- [ ] Ability for agents to join the inbound calls ( included in this PR
)

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>
Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>
Co-authored-by: iamsivin <iamsivin@gmail.com>
Co-authored-by: Pranav <pranav@chatwoot.com>

app/javascript/dashboard/stores/calls.js

@@ -0,0 +1,59 @@
+import { defineStore } from 'pinia';
+import TwilioVoiceClient from 'dashboard/api/channel/voice/twilioVoiceClient';
+import { TERMINAL_STATUSES } from 'dashboard/helper/voice';
+
+export const useCallsStore = defineStore('calls', {
+  state: () => ({
+    calls: [],
+  }),
+
+  getters: {
+    activeCall: state => state.calls.find(call => call.isActive) || null,
+    hasActiveCall: state => state.calls.some(call => call.isActive),
+    incomingCalls: state => state.calls.filter(call => !call.isActive),
+    hasIncomingCall: state => state.calls.some(call => !call.isActive),
+  },
+
+  actions: {
+    handleCallStatusChanged({ callSid, status }) {
+      if (TERMINAL_STATUSES.includes(status)) {
+        this.removeCall(callSid);
+      }
+    },
+
+    addCall(callData) {
+      if (!callData?.callSid) return;
+      const exists = this.calls.some(call => call.callSid === callData.callSid);
+      if (exists) return;
+
+      this.calls.push({
+        ...callData,
+        isActive: false,
+      });
+    },
+
+    removeCall(callSid) {
+      const callToRemove = this.calls.find(c => c.callSid === callSid);
+      if (callToRemove?.isActive) {
+        TwilioVoiceClient.endClientCall();
+      }
+      this.calls = this.calls.filter(c => c.callSid !== callSid);
+    },
+
+    setCallActive(callSid) {
+      this.calls = this.calls.map(call => ({
+        ...call,
+        isActive: call.callSid === callSid,
+      }));
+    },
+
+    clearActiveCall() {
+      TwilioVoiceClient.endClientCall();
+      this.calls = this.calls.filter(call => !call.isActive);
+    },
+
+    dismissCall(callSid) {
+      this.calls = this.calls.filter(call => call.callSid !== callSid);
+    },
+  },
+});