Remove `MANAGE_MESSAGES` once permissions split

[Jiralite]

On 12th January 2026 23rd February 2026, the permissions will be fully split. We should remove manage messages here if and when that happens:

discord.js/packages/discord.js/src/structures/Message.js

Lines 777 to 796 in ee988e3

	/**
	* Whether the message is pinnable by the client user
	* @type {boolean}
	* @readonly
	*/
	get pinnable() {
	const { channel } = this;
	if (this.system) return false;
	if (!this.guild) return true;
	if (!channel?.viewable) return false;
	const permissions = channel?.permissionsFor(this.client.user);
	if (!permissions) return false;
	return (
	permissions.has([PermissionFlagsBits.ReadMessageHistory, PermissionFlagsBits.PinMessages]) ||
	permissions.has([PermissionFlagsBits.ReadMessageHistory, PermissionFlagsBits.ManageMessages])
	);
	}

[Prigoistic]

i want this PR to be considered under hacktober fest