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/helper/specs/Timer.spec.js

@@ -0,0 +1,113 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
+import Timer from '../Timer';
+
+describe('Timer', () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+  });
+
+  afterEach(() => {
+    vi.restoreAllMocks();
+    vi.useRealTimers();
+  });
+
+  describe('constructor', () => {
+    it('initializes with elapsed 0 and no interval', () => {
+      const timer = new Timer();
+      expect(timer.elapsed).toBe(0);
+      expect(timer.intervalId).toBeNull();
+    });
+
+    it('accepts an onTick callback', () => {
+      const onTick = vi.fn();
+      const timer = new Timer(onTick);
+      expect(timer.onTick).toBe(onTick);
+    });
+  });
+
+  describe('start', () => {
+    it('starts the timer and increments elapsed every second', () => {
+      const timer = new Timer();
+      timer.start();
+
+      expect(timer.elapsed).toBe(0);
+
+      vi.advanceTimersByTime(1000);
+      expect(timer.elapsed).toBe(1);
+
+      vi.advanceTimersByTime(1000);
+      expect(timer.elapsed).toBe(2);
+
+      vi.advanceTimersByTime(3000);
+      expect(timer.elapsed).toBe(5);
+    });
+
+    it('calls onTick callback with elapsed value', () => {
+      const onTick = vi.fn();
+      const timer = new Timer(onTick);
+      timer.start();
+
+      vi.advanceTimersByTime(1000);
+      expect(onTick).toHaveBeenCalledWith(1);
+
+      vi.advanceTimersByTime(1000);
+      expect(onTick).toHaveBeenCalledWith(2);
+
+      expect(onTick).toHaveBeenCalledTimes(2);
+    });
+
+    it('resets elapsed to 0 when restarted', () => {
+      const timer = new Timer();
+      timer.start();
+
+      vi.advanceTimersByTime(5000);
+      expect(timer.elapsed).toBe(5);
+
+      timer.start();
+      expect(timer.elapsed).toBe(0);
+
+      vi.advanceTimersByTime(2000);
+      expect(timer.elapsed).toBe(2);
+    });
+
+    it('clears previous interval when restarted', () => {
+      const timer = new Timer();
+      timer.start();
+      const firstIntervalId = timer.intervalId;
+
+      timer.start();
+      expect(timer.intervalId).not.toBe(firstIntervalId);
+    });
+  });
+
+  describe('stop', () => {
+    it('stops the timer and resets elapsed to 0', () => {
+      const timer = new Timer();
+      timer.start();
+
+      vi.advanceTimersByTime(3000);
+      expect(timer.elapsed).toBe(3);
+
+      timer.stop();
+      expect(timer.elapsed).toBe(0);
+      expect(timer.intervalId).toBeNull();
+    });
+
+    it('prevents further increments after stopping', () => {
+      const timer = new Timer();
+      timer.start();
+
+      vi.advanceTimersByTime(2000);
+      timer.stop();
+
+      vi.advanceTimersByTime(5000);
+      expect(timer.elapsed).toBe(0);
+    });
+
+    it('handles stop when timer is not running', () => {
+      const timer = new Timer();
+      expect(() => timer.stop()).not.toThrow();
+      expect(timer.elapsed).toBe(0);
+    });
+  });
+});