feat: add weekly workflow to auto-update champions data

data/.github/workflows/update-champions.yml

@@ -0,0 +1,31 @@
+name: Update champions data
+
+on:
+  schedule:
+    # Every Thursday at 06:00 UTC (day after Riot's Wednesday patch)
+    - cron: "0 6 * * 4"
+  workflow_dispatch:
+
+jobs:
+  update:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+
+      - name: Run scraper
+        run: go run .
+
+      - name: Commit and push if changed
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "github-actions[bot]@users.noreply.github.com"
+          git add champions.json
+          git diff --cached --quiet && echo "No changes to commit" && exit 0
+          git commit -m "chore: update champions data to latest patch"
+          git push