fix: remove container isolation - use host runner environment

.gitea/workflows/syntax-check.yml

@@ -20,12 +20,9 @@ on:
 jobs:
   syntax-check:
     runs-on: linux,x86_64,docker
-    container:
-      image: alpine:3.19
     steps:
       - name: Checkout code
         run: |
-          apk add --no-cache git
           git clone --depth 1 "$(echo "${{ gitea.server_url }}" | sed "s|://|://oauth2:${{ gitea.token }}@|")/${{ gitea.repository }}.git" .
           git checkout -q ${{ github.sha }}
           echo "✓ Checkout complete"
@@ -34,7 +31,11 @@ jobs:
       - name: Install shellcheck
         run: |
           echo "Installing shellcheck..."
-          apk add --no-cache shellcheck
+          if command -v apk >/dev/null 2>&1; then
+            apk add --no-cache shellcheck
+          elif command -v apt-get >/dev/null 2>&1; then
+            apt-get update && apt-get install -y shellcheck
+          fi
           echo "✓ shellcheck installed"
 
       - name: Run bash syntax check