Fix connection reset instead of kick message

[purpurcof]

Problem

After successful verification, the player receives "Connection Reset" instead of the proper kick/disconnect message.
Fixes #476

Root Cause

In VerificationHandler.fail(), after calling user.disconnect() → closeWith(), a QuietDecoderException is thrown. The exception propagates to TailExceptionsHandler.exceptionCaught(), which calls ctx.close() immediately — before closeWith() can properly send the packet.

AbstractUnsafe.close() sets closeInitiated = true and nulls outboundBuffer, making the 50ms scheduled close from closeWith() a no-op. NioSocketChannel.doClose() calls javaChannel().close() right away. If the kernel receive buffer has unread data (a keep-alive from the client), the kernel sends TCP RST, discarding the pending disconnect data in the send buffer. The client sees "Connection Reset".

Fix

ProtocolUtil.closeWith() — setAutoRead(false) + 50ms close delay:

• setAutoRead(false) prevents client data from entering the kernel receive buffer
• 50ms delay gives the TCP stack time to transmit the disconnect/transfer packet before close() is called

SonarPacketDecoder.channelRead() — catch QuietDecoderException:

• The exception from fail() no longer reaches TailExceptionsHandler
• closeInitiated is not set prematurely
• closeWith() closes the channel after the delay as intended, not immediately

Made with Claude Opus 4.8

[lokspel]

#477

[jonesdevelopment]

Please include the name and model of the AI you used to make this commit/PR.

[jonesdevelopment]

Were you able to reproduce #595 and test that this PR fixes it?