feat: add auto-update licenses workflow for PRs

Create a new GitHub Action workflow that automatically updates the
LICENSE-3rdparty.csv file on pull requests when dependencies change.

The workflow:
- Triggers on changes to yarn.lock, package.json files, or .ddla-overrides
- Only runs on PRs from the same repository (not forks)
- Generates the license file using dd-license-attribution
- Commits and pushes changes back to the PR branch if needed
- Uses github-actions bot for commits

This ensures license files stay in sync with dependencies automatically.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 (1M context) <noreply@anthropic.com>

Author: typotter

.github/workflows/auto-update-licenses.yaml

@@ -0,0 +1,81 @@
+name: Auto-update Licenses
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+    paths:
+      - 'yarn.lock'
+      - 'package.json'
+      - '**/package.json'
+      - '.ddla-overrides'
+
+permissions:
+  contents: write
+  packages: read
+
+jobs:
+  update-licenses:
+    # Only run on PRs from the same repository (not forks)
+    if: github.event.pull_request.head.repo.full_name == github.repository
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out the repository
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        with:
+          ref: ${{ github.event.pull_request.head.ref }}
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Set up Python
+        uses: actions/setup-python@e797f83bcb11b83ae66e0230d6156d7c80228e7c # v6.0.0
+        with:
+          python-version: '3.11.12'
+
+      - name: Set up Node.js
+        uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v5.0.0
+        with:
+          node-version: '18'
+          cache: 'yarn'
+
+      - name: Set up Golang
+        uses: actions/setup-go@44694675825211faa026b3c33043df3e48a5fa00 # 6.0.0
+        with:
+          go-version: '1.23'
+
+      - name: Clone dd-license-attribution
+        run: |
+          git clone https://github.com/DataDog/dd-license-attribution.git /tmp/dd-license-attribution
+
+      - name: Install dd-license-attribution
+        run: |
+          python -m pip install --upgrade pip
+          python -m pip install /tmp/dd-license-attribution
+
+      - name: Install project dependencies
+        run: yarn install --frozen-lockfile
+
+      - name: Generate licenses
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: yarn licenses:generate
+
+      - name: Check for changes
+        id: check_changes
+        run: |
+          if git diff --quiet LICENSE-3rdparty.csv; then
+            echo "has_changes=false" >> $GITHUB_OUTPUT
+          else
+            echo "has_changes=true" >> $GITHUB_OUTPUT
+          fi
+
+      - name: Commit and push changes
+        if: steps.check_changes.outputs.has_changes == 'true'
+        run: |
+          git config --local user.email "github-actions[bot]@users.noreply.github.com"
+          git config --local user.name "github-actions[bot]"
+          git add LICENSE-3rdparty.csv
+          git commit -m "chore: auto-update LICENSE-3rdparty.csv
+
+Updated license file to reflect current dependencies.
+
+Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>"
+          git push