Improve duel client connection handling and bot room startup

[mercury233]

Summary

This PR improves duel client connection lifecycle handling, LAN room discovery, and bot room startup behavior.

Changes

• Move host name resolution out of menu_handler and into DuelClient.

  • Keeps menu handling easier to read.
  • Reduces coupling so menu_handler can be made cheaper to compile in the future.

• Use inet_pton for parsing numeric IPv4 addresses.

  • inet_pton is available on Windows since Vista, which is older than the supported Windows baseline.
  • DNS names are still resolved through evutil_getaddrinfo.

• Add named constants for duel client connection state.

  • Replaces magic bit values with explicit CONNECT_STATE_* names.
  • Makes the later connection-state fixes easier to follow.

• Replace the client is_closing flag with close_reason.

  • Makes normal stop and application-exit behavior explicit.
  • CLIENT_CLOSE_REASON_EXIT skips a little more UI/update handling than a normal stop.

• Fix disconnect handling while the client is connected but has not joined a room yet.

  • Previously, disconnecting in the CONNECTED state could leave the client stuck forever.
  • One reproducible case was connecting to an unreleated endpoint such as www.baidu.com:443.

• Track and cancel the client connect timeout event.

  • Prevents the timeout event allocated by event_new from leaking.
  • Cancels it after successfully joining a room or when the client thread exits.

• Disable the client bufferevent in StopClient.

  • Avoids extra processing after the client has already started closing.

• Fix LAN room refresh cleanup paths.

  • Failed setup paths now restore the refresh state and re-enable the refresh button.
  • Refresh completion now goes through a shared cleanup helper.

• Stop using gethostbyname for LAN room refresh.

  • Local IPv4 addresses are now collected with evutil_getaddrinfo.

• Make bot rooms private by default.

  • Bot rooms now bind to localhost, do not broadcast to LAN, and use a random available port by default.
  • This prevents other LAN users from unexpectedly seeing or watching bot games.
  • Random ports also allow multiple YGOPro instances on the same machine to host bot games without competing for the configured fixed port.
  • A new bot_room_public config option restores the previous public fixed-port behavior.

• Delay spawning the bot process until after the host has joined the room.

  • Avoids a theoretical startup race where the bot could connect before the host finishes entering the room.
  • If bot process startup fails, the host client disconnects and lets the server shut down through its normal host-leave path instead of calling NetServer::StopServer() directly.
  • Bot startup failure now shows a dedicated error message.
  • Closes fix spawn fail in BUTTON_BOT_START #3132 .

• Allow StopClient to stop the client from any active connection state, not only after successfully joining a room.

  • The close reason is updated even when no client connection is active, allowing an in-progress LAN refresh to suppress UI updates during application shutdown.

• Extend NetServer::StartServer.

  • Supports selecting the bind address and broadcast policy.
  • Reports the actual bound port when the operating system assigns one.

• Improve LAN discovery across multiple interfaces.

  • Duplicate local IPv4 addresses are ignored.
  • Failure on one local address no longer prevents trying the remaining addresses.

Future Work

• Deduplicate repeated UI reset calls such as btnCreateHost->setEnabled(true).
• Move DNS lookup to an asynchronous path.
• Move bot process startup to a separate thread.

[Copilot]

Pull request overview

This PR refactors and hardens the duel client/server connection lifecycle, improves LAN host discovery reliability, and changes bot-room startup to be private-by-default with randomized ports and delayed bot spawning.

Changes:

• Centralize host name resolution in DuelClient (using inet_pton for numeric IPv4 and evutil_getaddrinfo for DNS).
• Improve connection lifecycle correctness (explicit connect states/close reasons, connect-timeout tracking/cancellation, safer disconnect handling).
• Make bot rooms private by default (bind localhost, random port, no LAN broadcast unless configured), and defer bot process spawn until after the host joins.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
strings.conf	Adds a new system string for bot-start failure messaging.
gframe/netserver.h	Extends StartServer API to support bind IP, actual port output, and optional broadcast.
gframe/netserver.cpp	Implements bind-IP and ephemeral-port support and gates broadcast by configuration.
gframe/menu_handler.cpp	Moves hostname resolution into DuelClient and updates bot-room startup to use private-by-default randomized local binding.
gframe/game.h	Adds bot_room_public config and pending bot spawn state.
gframe/game.cpp	Loads/saves new bot_room_public option and adjusts client stop reason on exit.
gframe/duelclient.h	Adds explicit connect-state/close-reason constants and exposes ResolveHostName.
gframe/duelclient.cpp	Implements hostname resolution, connect-timeout tracking/cancellation, improved disconnect paths, safer LAN refresh cleanup, and delayed bot spawning.

Comments suppressed due to low confidence (1)

gframe/duelclient.cpp:4187

• SOCKADDR_IN local and SOCKADDR_IN sockTo are not zero-initialized before being passed to bind/sendto. Uninitialized padding/fields can trigger warnings (and, on some platforms, can be observable via kernel copies).

	SOCKADDR_IN local;
	local.sin_family = AF_INET;
	local.sin_port = htons(7922);
	SOCKADDR_IN sockTo;
	sockTo.sin_addr.s_addr = htonl(INADDR_BROADCAST);

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