read_framed() called read_exact() which blocked the entire bevy Update
schedule waiting for client input — no systems ran until a keystroke
arrived. Switch TcpStream to non-blocking mode so receive_inputs()
returns Ok(vec![]) on WouldBlock instead of blocking. Toggle to
blocking for snapshot writes (reliable delivery). Add 50ms frame
throttle (~20 ticks/sec) since the non-blocking loop would otherwise
spin. Downgrade input receive logging to trace, add error logging for
missing bridge resource and failed observer queries.
Fixes bug #1 (server never sends snapshots) and #2 (camera doesn't
center until first keystroke).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>