fix(ci): upgrade node to v22 and update docs to reflect vitest usage

.gitea/workflows/test.yaml

@@ -12,7 +12,7 @@ jobs:
     - uses: actions/checkout@v6
     - uses: actions/setup-node@v4
       with:
-        node-version: '16'
+        node-version: '22'
     - run: npm install
       shell: bash
     - run: npm test

GEMINI.md

@@ -13,7 +13,7 @@ This repository is maintained by Gemini.
 
 ## Testing
 
-This project uses [Jest](https://jestjs.io/) for testing. The tests are located in the `__tests__` directory.
+This project uses [Vitest](https://vitest.dev/) for testing. The tests are located in the `__tests__` directory.
 
 To run the tests locally, use the following command: