docs: add Alpine container usage and CI test

Add documentation for using setup-vp in Alpine containers with the
required gcompat compatibility packages. Add corresponding CI test job
to verify installation works in Alpine 3.21 containers.

Author: fengmk2

.github/workflows/test.yml

@@ -231,6 +231,33 @@ jobs:
         run: |
           echo "NODE_AUTH_TOKEN is set: ${NODE_AUTH_TOKEN:+yes}"
 
+  test-alpine-container:
+    strategy:
+      fail-fast: false
+      matrix:
+        version: [latest, alpha]
+    runs-on: ubuntu-latest
+    container:
+      image: alpine:3.21
+    steps:
+      - name: Install Alpine dependencies
+        run: apk add --no-cache bash curl gcompat libstdc++
+
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
+
+      - name: Setup Vite+ (${{ matrix.version }})
+        uses: ./
+        with:
+          version: ${{ matrix.version }}
+          run-install: false
+          cache: false
+
+      - name: Verify installation
+        run: vp --version
+
+      - name: Verify vp exec works
+        run: vp exec node -e "console.log('vp exec works in Alpine')"
+
   build:
     runs-on: ubuntu-latest
     steps:

README.md

@@ -110,6 +110,22 @@ steps:
       NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}
 ```
 
+### Alpine Container
+
+Alpine Linux uses musl libc instead of glibc. Install compatibility packages before using the action:
+
+```yaml
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    container:
+      image: alpine:3.21
+    steps:
+      - run: apk add --no-cache bash curl gcompat libstdc++
+      - uses: actions/checkout@v6
+      - uses: voidzero-dev/setup-vp@v1
+```
+
 ### Matrix Testing with Multiple Node.js Versions
 
 ```yaml