fix: relax SFU leaveAndClose constraints

[oliverlaz]

💡 Overview

Follow-up to #1846. call.leave() throws an error after unrecoverable FAST reconnect.
Our "leave" flow requires the client to announce its disconnect from the call to the SFU so the SFU can perform certain state cleanups faster. However, in the case described above, this isn't possible because the new SFU client never successfully connected to the SFU, and the signal WS was never established. This makes it impossible to send the announcement.

This PR adds better error handling and doesn't prevent the call instance disposal.

🎫 Ticket: https://linear.app/stream/issue/RN-241/refresh-call-state-after-a-failed-reconnect

[Copilot]

Pull Request Overview

This PR relaxes constraints in the leaveAndClose flow so that failures in the initial join task or notifying the SFU no longer prevent the call instance from being disposed.

• Moves await this.joinTask inside the try block to ensure join errors are caught.
• Continues to catch and log errors from notifyLeave without blocking disposal.

Comments suppressed due to low confidence (1)

packages/client/src/StreamSfuClient.ts:347

• Add unit tests that simulate failures in joinTask and notifyLeave to verify that leaveAndClose handles both errors gracefully and still allows disposal.

    try {