Pin exact versions of tailwindcss and @tailwindcss/*

[RobinMalfait]

This PR fixes an issue where installing a specific version of @tailwindcss/postcss and tailwindcss could still result in a version mismatch. This is because we were relying on ^4.0.6 for example instead of 4.0.6.

This PR now pins all these versions to prevent this:

❯ pnpm why tailwindcss
devDependencies:
@tailwindcss/postcss 4.0.5
├─┬ @tailwindcss/node 4.0.6
│ └── tailwindcss 4.0.6
└── tailwindcss 4.0.5