U06 — Sessions human report

Backlog: FIS-UX-012

Plan

Dual-wiki value surfaces in Studio: human report first, machine JSON in Advanced.

Do

1. Add GET /api/sessions/{id}/human in studio-server/studio_server.py (Markdown report).
2. Sessions UI renders human report when present; machine JSON under Advanced.

Check

scripts/fi-studio-ux-pdca/check-phase-gate.sh U06

Act

Wire human session endpoint and UI until U06 gate is green; then proceed to U07.