Open WebUI: Upload `metadata.knowledge_id` bypasses the knowledge-base write-access check (read-only users can add files to KB)

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. Prior to 0.10.0, the file upload path accepted metadata.knowledge_id and auto-linked uploaded files to a target knowledge base without applying the write-access check used by /api/v1/knowledge//file/add, allowing read-only knowledge-base users to add arbitrary files. This issue is fixed in version 0.10.0.