Refactor PushClient to improve robustness and error handling

[nglmercer]

The client state handling and network tasks have been significantly refactored to prevent resource deadlocks and unbounded memory growth. This includes proper buffering of media before publication, graceful shutdown procedures, and enhanced logging for connection status.

Key changes:

• Added bounded media buffers with LRU eviction for video/audio frames to prevent memory leaks
• Implemented structured background tasks for TCP reading/writing with proper cancellation
• Added sequence header caching and pre-publication buffering to ensure stream continuity
• Enhanced RTMP event handling to detect connection failures and reject streams appropriately
• Improved logging for connection status, errors, and shutdown events
• Simplified TLS connection setup and error propagation

[Juanperias]

i feel that this code is ai-generated but i cant prove it

[Juanperias]

There are a lot of comments that simply clutter up the code and add nothing (I know these comments are made with AI).

Example:

        // FIXED: Collapsed nested if let
        if let Some(meta) = &state.prepublish_metadata
            && let Ok(res) = state.session.publish_metadata(meta)
        {
            Self::send_packet(tx, res);
        }

        // FIXED: Collapsed nested if let
       // ...

[Juanperias]

My opinion is no, this should not be merged! As long as the code is still riddled with AI slop. If the solution is correct, then fine, but there wasn't human intervention, which makes reviewing the PR extremely tedious, not to mention that the AI tends to break the codebase.

Even so, @SergioRibera is the one managing the project, so the final decision is up to him