#5: BattleSession.RunAsync now unsubscribes FrameEmitted handlers
(-= OnFrameFromA/B) before termination and calls DisposeAsync on
both participants + the dispatch gate SemaphoreSlim afterward. This
unpins the session state from live delegates and releases the WS.
#6: Bare catch {} blocks replaced with filtered exception handlers
that silently swallow OperationCanceledException and WebSocketException
(expected at battle end) but log anything else at Warning. NREs and
other real bugs in handler threads are now visible instead of silently
eaten.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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