When the Desktop forcibly closes its WebSocket mid-write, asyncio logs a
full traceback for every pending connection-lost callback — 50+ identical
WinError 10054 (ConnectionResetError) lines per disconnect on Windows, the
equivalent ConnectionResetError/BrokenPipeError on POSIX. These are not
actionable: they are the expected side effect of the peer hanging up before
our writes drained.
Install a loop exception handler on the gateway serving loop that collapses
exactly this teardown class (ConnectionResetError/ConnectionAbortedError/
BrokenPipeError originating from _call_connection_lost) to a single debug
line, forwarding every other loop error to the existing/default handler
unchanged so genuine loop bugs still surface. Idempotent per loop.
