raiting: Fix typo: RaingState → RaitingState in rating.rs (#2744)

Fixes a typo in the internal struct name `RaingState` → `RaitingState`
in `crates/ui/src/rating.rs`.

## Description

Renamed the misspelled private struct `RaingState` to `RaitingState`
(two occurrences: struct definition and instantiation site).

## Screenshot

N/A — internal rename, no visual change.

## How to Test

No behavioral change. The struct is private; verify with `cargo build -p
gpui-component`.

## Checklist

- [ ] I have read the [CONTRIBUTING](../CONTRIBUTING.md) document and
followed the guidelines.
- [ ] Reviewed the changes in this PR and confirmed AI generated code
(If any) is accurate.
- [ ] Passed `cargo run` for story tests related to the changes.
- [ ] Tested macOS, Windows and Linux platforms performance (if the
change is platform-specific)

<!-- START COPILOT CODING AGENT SUFFIX -->

- Fixes #2743

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: huacnlee <5518+huacnlee@users.noreply.github.com>