fix(core-typings): add content field to MessageAttachmentDefault

Pin attachments include encrypted content from e2e messages.
Without this field, additionalProperties: false rejects the attachment.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ggazzo

apps/meteor/app/message-pin/server/pinMessage.ts

@@ -119,7 +119,7 @@ export async function pinMessage(message: IMessage, userId: string, pinnedAt?: D
 				text: originalMessage.msg,
 				author_name: originalMessage.u.username,
 				author_icon: getUserAvatarURL(originalMessage.u.username),
-				content: originalMessage.content,
+				...(originalMessage.content && { content: originalMessage.content }),
 				ts: originalMessage.ts,
 				attachments: attachments.map(recursiveRemove),
 			},
@@ -136,7 +136,7 @@ export const unpinMessage = async (userId: string, message: IMessage) => {
 	}
 
 	let originalMessage = await Messages.findOneById(message._id);
-	if (originalMessage == null || originalMessage._id == null) {
+	if (originalMessage?._id == null) {
 		throw new Meteor.Error('error-invalid-message', 'Message you are unpinning was not found', {
 			method: 'unpinMessage',
 			action: 'Message_pinning',

packages/core-typings/src/IMessage/MessageAttachment/MessageAttachmentDefault.ts

@@ -35,4 +35,7 @@ export type MessageAttachmentDefault = {
 	color?: string;
 
 	attachments?: MessageAttachment[];
+
+	/** Encrypted content from e2e messages, preserved in pin attachments */
+	content?: object;
 } & MessageAttachmentBase;