Revert tailwindcss v4 update (#16075)
## Summary
Revert the v4 update for now until the codebase is updated
(https://github.com/astral-sh/ruff/pull/16069).
Update renovate config to disable updating it.
## Test Plan
```console
$ npx --yes --package renovate -- renovate-config-validator
(node:98977) [DEP0040] DeprecationWarning: The `punycode` module is deprecated. Please use a userland alternative instead.
(Use `node --trace-deprecation ...` to show where the warning was created)
INFO: Validating .github/renovate.json5
INFO: Config validated successfully
```
And run `npm run build` in the `playground/` directory.