Migrate Nativewind To Uniwind

# Migrate NativeWind to Uniwind

Uniwind replaces NativeWind with better performance and stability. It requires **Tailwind CSS 4** and uses CSS-based theming instead of JS config.

## Pre-Migration Checklist

Before starting, read the project's existing config files to understand the current setup:
- `package.json` (NativeWind version, dependencies)
- `tailwind.config.js` / `tailwind.config.ts`
- `metro.config.js`
- `babel.config.js`
- `global.css` or equivalent CSS entry file
- `nativewind-env.d.ts` or `nativewind.d.ts`
- Any file using `cssInterop` or `remapProps` from `nativewind`
- Any file importing from `react-native-css-interop`
- Any ThemeProvider from NativeWind (`vars()` usage)

## Step 1: Remove NativeWind and Related Packages

Uninstall ALL of these packages (if present):
```bash
npm uninstall nativewind react-native-css-interop
# or
yarn remove nativewind react-native-css-interop
# or
bun remove nativewind react-native-css-interop
```

**CRITICAL**: `react-native-css-interop` is a NativeWind dependency that must be removed. It is commonly missed during migration. Search the entire codebase for any imports from it:
```bash
rg "react-native-css-interop" -g "*.{ts,tsx,js,jsx}"
```

Remove every import and usage found.

## Step 2: Install Uniwind and Tailwind 4

```bash
npm install uniwind tailwindcss@latest
# or
yarn add uniwind tailwindcss@latest
# or
bun add uniwind tailwindcss@latest
```

Ensure `tailwindcss` is version 4+.

## Step 3: Update babel.config.js

Remove the NativeWind babel preset:
```js
// REMOVE this line from presets array:
// 'nativewind/babel'
```

No Uniwind babel preset is needed.

## Step 4: Update metro.config.js

Replace NativeWind's metro config with Uniwind's. `withUniwindConfig` must be the **outermost wrapper**.

**Before (NativeWind):**
```js
const { withNativeWind } = require('nativewind/metro');
module.exports = withNativeWind(config, { input: './global.css' });
```

**After (Uniwind):**
```js
const { getDefaultConfig } = require('expo/metro-config');
// For bare RN: const { getDefaultConfig } = require('@react-native/metro-config');
const { withUniwindConfig } = require('uniwind/metro');

const config = getDefaultConfig(__dirname);

module.exports = withUniwindConfig(config, {
  cssEntryFile: './global.css',
  polyfills: { rem: 14 },
});
```

`cssEntryFile` must be a **relative path string** from project root (e.g. `./global.css` or `./app/global.css`).
Do **not** use absolute paths or `path.resolve(...)` / `path.join(...)` for this option.

```js
// ❌ Broken
cssEntryFile: path.resolve(__dirname, 'app', 'global.css')

// ✅ Correct
cssEntryFile: './app/global.css'
```

**Always set `polyfills.rem` to 14** to match NativeWind's default rem value and prevent spacing/sizing differences after migration.

If the project uses custom themes beyond `light`/`dark` (e.g. defined via NativeWind's `vars()` or a custom ThemeProvider), register them with `extraThemes`. Do NOT include `light` or `dark` — they are added automatically:

```js
module.exports = withUniwindConfig(config, {
  cssEntryFile: './global.css',
  polyfills: { rem: 14 },
  extraThemes: ['ocean', 'sunset', 'premium'],
});
```

Options:
- `cssEntryFile` (required): relative path string to CSS entry file (from project root)
- `polyfills.rem` (required for migration): set to `14` to match NativeWind's rem base
- `extraThemes` (required if project has custom themes): array of custom theme names — do NOT include `light`/`dark`
- `dtsFile` (optional): path for generated TypeScript types, defaults to `./uniwind-types.d.ts`
- `debug` (optiona