feat(protbot): add headless MHF protocol bot as cmd/protbot

Copy MHBridge into the Erupe module as cmd/protbot/ so it can be
built, tested, and maintained alongside the server. The bot
implements the full sign → entrance → channel login flow and
supports lobby entry, chat, session setup, and quest enumeration.

The conn/ package keeps its own Blowfish crypto primitives to avoid
importing erupe-ce/config (which requires a config file at init).

cmd/protbot/scenario/logout.go

@@ -0,0 +1,17 @@
+package scenario
+
+import (
+	"fmt"
+
+	"erupe-ce/cmd/protbot/protocol"
+)
+
+// Logout sends MSG_SYS_LOGOUT and closes the channel connection.
+func Logout(ch *protocol.ChannelConn) error {
+	fmt.Println("[logout] Sending MSG_SYS_LOGOUT...")
+	if err := ch.SendPacket(protocol.BuildLogoutPacket()); err != nil {
+		ch.Close()
+		return fmt.Errorf("logout send: %w", err)
+	}
+	return ch.Close()
+}