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/Timer.js

@@ -0,0 +1,28 @@
+export default class Timer {
+  constructor(onTick = null) {
+    this.elapsed = 0;
+    this.intervalId = null;
+    this.onTick = onTick;
+  }
+
+  start() {
+    if (this.intervalId) {
+      clearInterval(this.intervalId);
+    }
+    this.elapsed = 0;
+    this.intervalId = setInterval(() => {
+      this.elapsed += 1;
+      if (this.onTick) {
+        this.onTick(this.elapsed);
+      }
+    }, 1000);
+  }
+
+  stop() {
+    if (this.intervalId) {
+      clearInterval(this.intervalId);
+      this.intervalId = null;
+    }
+    this.elapsed = 0;
+  }
+}