* feat(s3): add short access links * refactor(s3): extract access link sdk core * fix(s3): resolve access link sdk alias in pro tests * fix: persist invoke uploaded files * feat: support s3 short redirect download mode * docs: add s3 refactor design docs * refactor: improve s3 upload policy handling * fix: support aborting chat file uploads * feat: support public download shortlink prefix * fix: resolve public shortlink file metadata * fix: restore shortlink media in chat context * fix: persist sandbox files with chat lifecycle * fix: align dropped files with upload config * fix: reject mismatched explicit upload types * fix: await dataset preview access links * fix: align pro chat file persistence * fix(chat): secure draft file upload policies * fix(chat): preserve first-turn media file types * perf(s3): reduce download alias lease writes * fix(chat): preserve first-turn media metadata * perf(s3): batch download access link issuance * fix(s3): release aborted proxy download streams * test(s3): align checks with stream lifecycle * fix: resolve shortlink CI build failures * docs: consolidate s3 refactor design
