Add SCSS unit tests for mixins, utilities, and helpers (#2699)

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

.github/workflows/build.yml

@@ -1,4 +1,4 @@
-name: Test build
+name: Build
 
 on:
   pull_request: null
@@ -7,7 +7,7 @@ permissions:
   contents: read
 
 jobs:
-  test:
+  build:
     runs-on: ubuntu-latest
     steps:
       - name: Clone repository

.github/workflows/js-tests.yml

@@ -33,5 +33,5 @@ jobs:
         run: pnpm exec playwright install --with-deps chromium
         working-directory: core
 
-      - name: Run tests
-        run: pnpm --filter @tabler/core test
+      - name: Run JS tests
+        run: pnpm --filter @tabler/core test:js

.github/workflows/scss-tests.yml

@@ -0,0 +1,33 @@
+name: SCSS Tests
+
+on:
+  pull_request: null
+  push:
+    branches:
+      - dev
+      - main
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Clone repository
+        uses: actions/checkout@v7
+
+      - name: Install PNPM
+        uses: pnpm/action-setup@v6
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v6
+        with:
+          node-version-file: '.nvmrc'
+          cache: 'pnpm'
+
+      - name: Install dependencies
+        run: pnpm install
+
+      - name: Run SCSS tests
+        run: pnpm --filter @tabler/core test:scss