Adds generateMentorObjectKey helper producing
<projectName>/mentorship/<timestamp>-<file>. Replaces the
client-supplied bucket/objectKey on workspaceUploadFile with an
HMAC-signed upload token that binds bucket, objectKey, uploader,
and a 1h expiry — paths can no longer be forged from the client.
Adds workspaceGetUploadUrl, workspaceGetFiles,
workspaceGetFileDownloadUrl, workspaceDeleteFile procedures with
mentor-or-team-member auth. Builds <WorkspaceFilesPanel> and
wires it into the mentor workspace Files tab and the applicant
/applicant/mentor page. Replaces the file-promotion-panel mock
array with a real workspaceGetFiles query.
Tests cover token sign/verify (5), key construction (5), and
end-to-end procedure flow including auth + tampered tokens (7).
Spec: docs/superpowers/specs/2026-04-28-mentor-round-readiness-design.md §F.1
Plan: docs/superpowers/plans/2026-04-28-pr2-mentor-workspace-files.md
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
