chore: add PR automation workflows for triage, formatting, staleness, and overlap detection (#263)

.github/workflows/dependabot-approve.yml

@@ -0,0 +1,35 @@
+name: Dependabot Auto-Approve
+
+on:
+  pull_request:
+    branches: [main]
+
+permissions:
+  contents: read
+  pull-requests: write
+
+jobs:
+  approve:
+    name: Auto-Approve
+    if: github.actor == 'dependabot[bot]'
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - name: Fetch Dependabot metadata
+        id: metadata
+        uses: dependabot/fetch-metadata@d7267f607e9d3fb96fc2fbe83e0af444e40b2048 # v2.4.0
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Auto-approve patch and minor updates
+        if: steps.metadata.outputs.update-type != 'version-update:semver-major'
+        uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea # v7.0.1
+        with:
+          script: |
+            await github.rest.pulls.createReview({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              pull_number: context.payload.pull_request.number,
+              event: 'APPROVE',
+              body: 'Auto-approved: ${{ steps.metadata.outputs.update-type }} update for ${{ steps.metadata.outputs.dependency-names }}.',
+            });