Clarify the workflow value and verification path

[shinpr]

Summary

• frame the workflow around converging Claude exploration on an agreed outcome
• show the complete path from scope agreement through task-level quality gates and independent final review
• explain structural scale through product and design decisions instead of document count
• keep lightweight helper recipes out of the primary onboarding path
• align the background reading with verification, context separation, boundary control, and phase-specific exploration

Validation

• git diff --check
• README-only change