docs: revalidate competitive matrix

[okyrychenko-dev]

Summary

• revalidate the comparison against @ebay/nice-modal-react@1.2.13 as of 2026-09-13
• cover typing, lifecycle behavior, provider isolation, React compatibility, SSR/RSC, imperative access, rendering, ccessibility, ergonomics, package cost, performance, and maintenance
• distinguish verified behavior, published contracts, documentation, and implementation architecture
• replace the inaccurate global-state comparison with a precise description of Nice Modal’s provider-local reducer and module-level imperative routing
• document the typed-definition and provider-bound registry trade-offs
• add pnpm run competitive:check to reproduce the competitor package-cost measurement
• report package-cost results without claiming a universal size or performance winner
• update the discriminated-union example to use named result branches
• correct the current Radix-based shadcn Dialog integration, including controlled dismissal, accessible title composition, and exit timing
• document that the provider-wide shadcn renderer requires content-only modals and a compatible custom confirmation modal

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!