chore(skill): add version check to rivetkit skill (#4491)

# Description

Please include a summary of the changes and the related issue. Please also include relevant motivation and context.

## Type of change

- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
- [ ] This change requires a documentation update

## How Has This Been Tested?

Please describe the tests that you ran to verify your changes.

## Checklist:

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my feature works
- [ ] New and existing unit tests pass locally with my changes

Author: NathanFlurry

website/src/metadata/skill-base-rivetkit.md

@@ -61,6 +61,16 @@ Use that canonical URL when citing, not the reference file path.
 - React client → `https://rivet.dev/docs/clients/react`
 - Self-hosting on Kubernetes → `https://rivet.dev/docs/self-hosting/kubernetes`
 
+## Version Check
+
+Before starting any work, check if the user's project is on the latest version of RivetKit (latest: {{RIVETKIT_VERSION}}). Look at the `rivetkit` version in the user's `package.json` (check both `dependencies` and `devDependencies`). If the installed version is older than {{RIVETKIT_VERSION}}, inform the user and suggest upgrading:
+
+```bash
+npm install rivetkit@{{RIVETKIT_VERSION}}
+```
+
+If the user also uses `@rivetkit/react`, `@rivetkit/next-js`, or other `@rivetkit/*` client packages, suggest upgrading those too. Outdated versions may have known bugs or missing features that cause issues.
+
 ## First Steps
 
 1. Install RivetKit (latest: {{RIVETKIT_VERSION}})