docs: preserve decision and tooling research context

[nothingnesses]

Summary

• Restore the reviewed 114-decision report without byte changes. Its earlier PR merged into a branch after that branch merged into main.
• Preserve the alternatives study and Rust library trial in one sanitised report, with separate OpenShell and VeriGuard assessments.
• Add README links and a bounded work brief.

Validation

• Host just ci passed before review, after the wording correction and after the commit.
• The historical report retains SHA-256 0d8c9842faca6dcb579cca9d180c9c3c4e5fd2e7786c8980df8fe010d2aa9d46.
• Independent review identified three wording violations. The scoped correction passed focused verification.
• The committed tree matches the verified tree, 688505f52a2bdae85b4dd93663abde82db90f9ac.

Boundary

This PR changes documentation only. It adds no dependency or controller implementation and adopts no research candidate. The PR contains no raw sessions or private execution evidence. The work step remains active.