docs: overhaul ROADMAP.md with audit-driven DX and UX improvement proposals

- Add Full-Repository Audit section with quantified findings
- Re-prioritize: DX (P1) > UX (P2) > Component Excellence (P3) > Docs (P4)
- P1: Zero-friction onboarding, JSDoc, error codes, CLI polish, 10 missing READMEs
- P2: Console i18n, accessibility, performance at scale, architecture cleanup
- P3: Component audit, field polish, test coverage 80→90%, Storybook 68→91+
- P4: Guides, API reference, Storybook as living docs, architecture docs
- Update success metrics with DX/UX criteria and measurement methods
- Update risk management with DX/UX-specific risks and mitigations

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot