refactor(examples): update CSS variable names to use consistent --color- prefix in tailwind examples (#10662)
### Description
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Tailwind CSS v4 uses the `--color-*` convention for custom properties.
In the current example file at
[`examples/with-tailwind/packages/tailwind-config/shared-styles.css`](https://github.com/vercel/turborepo/blob/main/examples/with-tailwind/packages/tailwind-config/shared-styles.css),
the custom color variables do **not** use the `--color-` prefix, which
causes them not to work correctly with Tailwind v4.
This PR updates the variable names to follow the correct naming
convention, allowing them to be used properly with Tailwind's color
system.
#### Before:
```css
@theme {
--blue-1000: #2a8af6;
--purple-1000: #a853ba;
--red-1000: #e92a67;
}
```
#### After:
```css
@theme {
--color-blue-1000: #2a8af6;
--color-purple-1000: #a853ba;
--color-red-1000: #e92a67;
}
```
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turborepo
40dff7bd - refactor(examples): update CSS variable names to use consistent --color- prefix in tailwind examples (#10662)
