feat: add CSS @property rule support

[YevheniiKotyrlo]

Problem

Tailwind CSS v4 shadow and ring utilities don't work on React Native. Two root causes:

1. Inset shadows — (Fixed in feat: add inset shadow parsing support #277)
2. Missing @property defaults — Tailwind v4 uses ~53 @property declarations to register custom property initial values (e.g., --tw-shadow, --tw-ring-shadow). Without parsing these, ring utilities produce boxShadow: []. (Fixed here)

Stacking

This branch is based on #277 (2 commits total). Please review and merge #277 first — once it lands, this PR's diff will auto-reduce to just the @property changes. Until then, the diff includes both PRs.

Individual commits:

• 7aefcac — feat: add inset shadow parsing support #277: inset shadow parsing (view)
• 64a2be8 — this PR: @Property support

What this replaces

Previously, react-native-css faked -moz-orient support to trigger Tailwind's @supports fallback path. This fallback injected universal variable defaults which interfered with class-level overrides. The @property approach is generic and framework-agnostic — this is the direction suggested during the #277 review.

Changes (this PR only)

src/compiler/compiler.ts

Parse @property rules, extract initial-value into root variables via extractPropertyRule / parsePropertyInitialValue. Handles length, number, percentage, color, angle, token-list, custom-ident, and repeated component types.

src/compiler/stylesheet.ts

Add addRootVariable() public method following the existing variable storage pattern.

src/compiler/supports.ts

Remove the -moz-orient hack (no longer needed).

src/native/styles/shorthands/_handler.ts

Allow StyleFunction values (calc, var) to pass type checks in the shorthand handler. These are unresolved at pattern-match time but resolve to the correct type at runtime.

src/native/styles/shorthands/box-shadow.ts

Fix color type from "string" to "color" to accept platform color objects (e.g., PlatformColor from currentcolor resolution).

Tests

• 10 compiler tests for @property parsing
• 2 runtime tests for box-shadow @Property defaults and currentcolor matching

[danstepanov]

@YevheniiKotyrlo mind rebasing this with main?

[YevheniiKotyrlo]

Done — rebased on latest main. Stack is clean: commit 1 is #277 (inset parsing), commit 2 is this PR (@Property support). All quality gates pass.