feat: add native filter utilities

[e-simpson]

Summary

This PR adds composable Tailwind-compatible utilities for every React Native filter with a safe native mapping: brightness, blur, contrast, grayscale, hue rotation, invert, saturate, sepia, drop shadow, and filter-none.

Changes

• Adds percentage, full-effect, preset, negative-angle, and arbitrary forms for the supported filter families.
• Adds Tailwind blur and drop-shadow scales plus structured arbitrary native shadows such as drop-shadow-[0_4px_4px_#00000080].
• Composes distinct native filter functions and keeps last-wins behavior for duplicate functions.
• Emits composed filters in Tailwind's canonical order: blur, brightness, contrast, grayscale, hue-rotate, invert, saturate, sepia, then drop-shadow.
• Makes filter-none win regardless of class-string order, matching Tailwind's generated CSS.

The canonical order is intentional: CSS filter functions and React Native filter arrays are sequential, so changing their order can change rendering. Tailwind's CSS-variable composition provides one stable order independent of markup ordering, and this PR preserves that contract natively.

Native boundaries

• Brightness works on iOS and Android.
• Blur, contrast, drop shadow, grayscale, hue rotation, invert, saturate, and sepia are currently Android-only in React Native.
• Filters require native filter support and imply clipping through overflow: hidden.
• The existing opacity-* utility remains the native opacity style property.
• Standalone drop-shadow-{color} is not emitted because React Native requires a complete structured dropShadow object. Structured arbitrary shadows can include preset or custom colors.

Example

<View className="drop-shadow-md sepia hue-rotate-45 brightness-110 blur-sm" />

// filter: [
//   { blur: 8 },
//   { brightness: 1.1 },
//   { hueRotate: "45deg" },
//   { sepia: 1 },
//   { dropShadow: { ... } },
// ]

Validation

• bun run spec -- src/parser/filters.test.ts src/utils/mergeStyles.test.ts — 39 passed
• bun run check
• bun run lint
• bun run format:check