PYSEC-2026-2742 Open WebUI's process_files_batch() endpoint missing ownership check, allows unauthorized file overwrite

Summary Any authenticated user can overwrite any file's content by ID through the POST /api/v1/retrieval/process/files/batch endpoint. The endpoint performs no ownership check, so a regular user with read access to a shared knowledge base can obtain file UUIDs via GET /api/v1/knowledge/id/files a...