[feature]: allow attaching multiple files at once to a work item

Is there an existing issue for this? • I have searched the existing issues Summary Work item attachments can only be added one file at a time. In apps/web/core/components/issues/attachment/attachment-upload.tsx the dropzone is configured with multiple: false, and onDrop takes only the first entry: Two consequences: 1. The file picker does not let you select more than one file. 2. If you drag and drop several files at once, only the first is uploaded and the rest are silently discarded — no error, no indication. That part reads more like a bug than a limitation. Why should this be worked on? Attaching a set of files is the normal case, not the exception: a handful of screenshots for a bug report, a log bundle, several exported documents. Right now each file is a separate drag-and-wait cycle, and dropping them together looks like it worked while quietly dropping all but one. Backend impact None. IssueAttachmentV2Endpoint.post already creates exactly one FileAsset and on…