Erdős Problem 1148: status mismatch (repo=solved, erdosproblems.com=formally solved)

The status of [Erdős problem 1148](https://www.erdosproblems.com/1148) appears to have changed.

- **[This repo](http://github.com/google-deepmind/formal-conjectures/blob/main/FormalConjectures/ErdosProblems/1148.lean)**: `solved` (in `FormalConjectures/ErdosProblems/1148.lean`)
- **[erdosproblems.com/1148](https://www.erdosproblems.com/1148)**: `formally solved`

Please verify and update the `@[category research ...]` annotation if appropriate.

Start by comparing the current status in FormalConjectures/ErdosProblems/1148.lean with the linked erdosproblems.com/1148 page and inspect its @[category research ...] annotation. Verify which status is correct, update the annotation if needed, and confirm the repository and external status agree.

Written by the indexing model from the issue text.