ci: add GitHub Actions workflowautomated sync

Author: arnav-on-code

.github/workflows/sync.yml

@@ -0,0 +1,45 @@
+name: LeetCode Sync
+
+on:
+  workflow_dispatch:
+
+  schedule:
+    - cron: "0 */6 * * *"   # Every 6 hours
+
+jobs:
+  sync:
+
+    runs-on: ubuntu-latest
+
+    steps:
+
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.13"
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r requirements.txt
+
+      - name: Run LeetCode Sync
+        env:
+          LEETCODE_SESSION: ${{ secrets.LEETCODE_SESSION }}
+          CSRF_TOKEN: ${{ secrets.CSRF_TOKEN }}
+          LEETCODE_USERNAME: ${{ secrets.LEETCODE_USERNAME }}
+          GITHUB_USERNAME: ${{ secrets.GITHUB_USERNAME }}
+          GITHUB_EMAIL: ${{ secrets.GITHUB_EMAIL }}
+
+        run: |
+          python main.py
+
+      - name: Push changes
+        run: |
+          git config --global user.name "${{ secrets.GITHUB_USERNAME }}"
+          git config --global user.email "${{ secrets.GITHUB_EMAIL }}"
+
+          git push