test: add Vitest client-side test suite + CI

.github/workflows/pull-request.yaml

@@ -49,6 +49,24 @@ jobs:
       - name: Run svelte-check
         run: npm run check
 
+  test:
+    name: Run Vitest
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node: [24.x]
+    steps:
+      - name: Check out Project Git repository
+        uses: actions/checkout@v6
+
+      - name: Init Nodejs
+        uses: MapColonies/shared-workflows/actions/init-npm@init-npm-v1
+        with:
+          node-version: ${{ matrix.node }}
+
+      - name: Run tests
+        run: npm run test
+
   helm-lint:
     name: Run Helm lint Check
     runs-on: ubuntu-latest