chore: Add Semgrep CI integration (#296)

Add Semgrep CI integration

Author: son-oz

.github/workflows/semgrep.yml

@@ -0,0 +1,47 @@
+name: Semgrep
+
+on:
+  # Scan changed files in PRs (diff-aware scanning):
+  pull_request: {}
+  # Scan on-demand through GitHub Actions interface:
+  workflow_dispatch: {}
+  # Scan mainline branches and report all findings:
+  push:
+    branches: ["main"]
+  # Schedule the CI job (this method uses cron syntax):
+  schedule:
+    - cron: '15 11 * * *' # Sets Semgrep to scan every day at 11:15 UTC.
+
+jobs:
+  semgrep:
+    name: semgrep/ci
+    runs-on: ubuntu-latest
+    permissions:
+      security-events: write
+      contents: read
+      actions: read
+
+    container:
+      image: semgrep/semgrep@sha256:85f9de554201cc891c470774bb93a7f4faf41ea198ddccc34a855b53f7a51443  # v1.127.1
+
+    # Skip any PR created by dependabot to avoid permission issues:
+    if: (github.actor != 'dependabot[bot]')
+
+    steps:
+      - name: Harden Runner
+        uses: step-security/harden-runner@0634a2670c59f64b4a01f0f96f84700a4088b9f0  # v2.12.0
+        with:
+          egress-policy: audit
+      - name: Checkout code
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683  # v4.5.4
+      # Run the "semgrep ci" command on the command line of the docker image.
+      - run: semgrep ci --sarif > semgrep.sarif
+        env:
+          # Connect to Semgrep AppSec Platform through your SEMGREP_APP_TOKEN.
+          SEMGREP_APP_TOKEN: ${{ secrets.SEMGREP_APP_TOKEN }}
+
+      - name: Upload SARIF file for GitHub Advanced Security Dashboard
+        uses: github/codeql-action/upload-sarif@fca7ace96b7d713c7035871441bd52efbe39e27e  # v3.28.19
+        with:
+          sarif_file: semgrep.sarif
+