ci(workspace): add pnpm audit workflow to scan dependencies

introduce automated security scanning for dependencies by running `npm audit` in pull requests.
this ensures vulnerabilities are caught earlier in the development cycle and increases visibility for reviewers.

Closes #153

Author: TharakaUJ

.github/workflows/npm-audit.yml

@@ -0,0 +1,58 @@
+# -------------------------------------------------------------------------------------
+#
+# Copyright (c) 2024, WSO2 LLC. (https://www.wso2.com).
+#
+# WSO2 LLC. licenses this file to you under the Apache License,
+# Version 2.0 (the "License"); you may not use this file except
+# in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+#
+# --------------------------------------------------------------------------------------
+
+# This workflow will perform a security audit on the codebase.
+
+name: Security Audit
+
+on:
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  audit:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 18
+
+      - name: Install pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 9
+
+      - name: Install dependencies
+        run: pnpm install
+
+      - name: Run audit
+        run: |
+          pnpm audit --json > audit-results.json || true
+          pnpm audit --audit-level=high
+
+      - name: Upload audit results
+        uses: actions/upload-artifact@v4
+        with:
+          name: pnpm-audit-report
+          path: audit-results.json