fix: map tint utilities to native props - #1839

Summary

• Replace the removed @prop directive in tint-* with @nativeMapping.
• Use block syntax so Tailwind preserves the mapping while expanding the custom utility.
• Add a regression test confirming tint-black reaches the top-level tint prop and leaves style empty.

Fixes #1837

Why

react-native-css 3 recognizes @nativeMapping, not the old @prop directive. Without the mapping, tint-black compiles to style.tint, which React Native ignores for the intended component prop. A statement-form unknown at-rule is also dropped during Tailwind utility expansion; the block form survives and compiles the color to the native tint path.

Test plan

• Confirmed the new regression test fails before the fix with { style: { tint: "#000" } }.
• yarn install --immutable
• yarn lint
• yarn typecheck
• yarn build
• yarn test --maxWorkers=2 --coverage (7 suites, 36 tests)
• yarn example expo export --platform web
• yarn pack --dry-run