Run C FI on blocking threads and fix audio queue
Run blocking C FFI on web::block to avoid blocking Actix worker
threads and prevent nested tokio/reqwest::blocking contexts. Use
audio_queue_post with a static audio_resume_info so pointers remain
valid when posting from non-Rockbox threads. Also skip live metadata
lookups for HTTP tracks, ignore Rockbox UPnP renderers, and improve
Bluetooth availability checking.