sandbox phase 5 (UI): PDP submission console (preflight → submit → receipt) #121

Parent: #116 · Spec: docs/superpowers/specs/2026-05-02-sis-pdp-ar-sandbox-design.md

Scope

• Route /sandbox/pdp: three-step horizontal flow (not a wizard modal).
• Preflight: green/yellow/red triage panel with row counts and inline anomaly samples (no "view details" hide).
• Submit: deliberate single button, 1.5s confirmation pause, writes via phase-2 submit pass.
• Receipt: bookmarkable page with row counts, errors, coercions, diff vs. previous submission, downloadable PDF.
• Amber (#B8732C) stage tint. Density drops to ~6–8 rows (calmer than SIS room).

Acceptance

• Preflight runs without writing and shows structured triage
• Submit produces a receipt with stable URL
• Receipt links upstream to source SIS rows
• Receipt is downloadable as PDF

Estimate: 3–4 days. Depends on phase 2.