fix: observe AVPlayerItem.status for HLS streaming auto-start

[tahakocal]

Problem

When playing HLS (m3u8) streams, audio doesn't start automatically on the first play() call. The player reports a "playing" state, but no audio is heard. Pausing and playing again makes audio work.

Root Cause

When play() is called:

1. playWhenReady is set to true
2. applyAVPlayerRate() is called to set the AVPlayer rate
3. But AVPlayerItem.status is still .unknown at this point
4. AVPlayer ignores rate changes when the item status is not .readyToPlay

Later, when the item becomes ready (status = .readyToPlay), nothing triggers playback because status changes were not being observed.

Solution

This PR adds observation of AVPlayerItem.status:

1. AVPlayerItemObserver.swift: Added status to the observed keypaths and a new delegate method item(didUpdateStatus:)
2. AVPlayerWrapper.swift: Implemented the delegate method to call applyAVPlayerRate() when status becomes .readyToPlay and playWhenReady is true

Why This Works

Timeline before fix:
play() called → playWhenReady=true → applyRate() → item.status=.unknown → ❌ No audio

Timeline after fix:
play() called → playWhenReady=true → applyRate() → item.status=.unknown → (no audio yet)
→ item.status=.readyToPlay → applyRate() → ✅ Audio plays!

Testing
Tested with:

• HLS streams (m3u8)
• MP3 files (no regression)
• Various network conditions

References
From Apple's WWDC 2016 session on AVFoundation:
"You should observe the status property of AVPlayerItem and only begin playback when status is .readyToPlay"