Added Advanced Chat support

• Added the ADVANCED_CHAT_CHANNEL mention type
• Allows mentioning players in a specific Advanced Chat channel
• If Advanced Chat is not installed, this mention type is ignored

Added new setting

• Added the require_same_channel setting
• Default value: true
• When enabled, users can only mention the Advanced Chat channel they are currently in

Changed handling for invalid input/actions

• Previously, invalid mention targets were silently ignored, but now message sending is blocked
• Non-existent teams, players, worlds, or Advanced Chat channels
• Invalid selectors
• Trying to mention again while mention cooldown is active
• Using HOVER_ITEM or SHOW_ITEM when there is no item to display

Added block reason output

• When a message is blocked, the reason is shown to the user as a red system message when available

Changed BLOCK style

• The BLOCK style can now pass a block message along with it