feat: add studio course draft workflow

[OpadijoIdris]

Summary

This PR adds a trusted-creator course authoring draft workflow so course proposals can be created, updated, submitted for review, and approved without requiring a code deploy.

It introduces a reputation-gated draft creation flow based on LRN balance, adds server-side draft lifecycle endpoints for authors and admins, wires minimal studio authoring/review UI entry points, and includes regression tests covering threshold enforcement, autosave/update, submission, and approval/materialization.

Type of Change

• New feature
• Bug fix
• Smart contract change
• Documentation
• Breaking change
• Other (please describe)

Checklist

• Tests added or updated
• No hardcoded secrets or private keys
• If contract change: cargo test passes
• If frontend change: npm run typecheck passes
• If backend change: npm test passes
• Related issues linked (Closes #...)
• Self-review completed
• Code follows project style guidelines

Screenshots (if applicable)

N/A

Testing

• Added regression tests for:
  • draft creation threshold enforcement
  • autosave/content updates
  • submit-for-review flow
  • approve/materialize flow

Additional Notes

This change is intended as a first-pass implementation of the draft workflow and can be refined further once the full studio authoring experience is designed.

Closes #1029

[Anuoluwapo25]

please fix checks

[Anuoluwapo25]

Hi @OpadijoIdris , Just want to confirm if you are still working on this issue