Groom: td-df820a with JTBD problem statement and success criteria

**Why this matters:** td-df820a is a central onboarding work item but is currently framed as a broad concept with mixed discovery/implementation content. Without a precise problem statement and success criteria, execution slicing and prioritization across Glenn/Jared/Gary will remain ambiguous.\n\n**Scope:** Define the primary merchant job for onboarding redesign, baseline severity (activation/value metrics), explicit in-scope/out-of-scope outcomes, and decision-grade success criteria for the next implementation cycle.\n\n**Source signal:** td-df820a description + handoff log breadth; referral overview and north-star strategy docs.