docs: add open issues resolution ultraplan (#577)

## Summary
- Add a sequenced, evidence-led plan for the 15 currently open
repository issues.
- Document repo recon findings, dependencies, safety boundaries, and
per-issue acceptance criteria.
- Flag stale issue assumptions for live revalidation before
implementation.

## Validation
- 

Documentation only; no issue state or repository code changed.

Co-authored-by: hyperpolymath <6759885+hyperpolymath@users.noreply.github.com>
Co-authored-by: arena-agent <297053741+arena-agent@users.noreply.github.com>

Author: 3 people