Add github actions

.github/workflows/check-pr-size.yml

@@ -0,0 +1,47 @@
+name: Check PR size
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+
+jobs:
+  check_pr_size:
+    runs-on: ubuntu-latest
+    timeout-minutes: 1
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+
+      - name: Calculate changed lines
+        id: diff_check
+        run: |
+          # Get the target branch commit (base) and the PR branch commit (head)
+          BASE_SHA="${{ github.event.pull_request.base.sha }}"
+          HEAD_SHA="${{ github.event.pull_request.head.sha }}"
+          echo "Base SHA: $BASE_SHA"
+          echo "Head SHA: $HEAD_SHA"
+
+          # Compute the merge base between the two branches
+          MERGE_BASE=$(git merge-base "$HEAD_SHA" "$BASE_SHA")
+          echo "Merge Base: $MERGE_BASE"
+
+          # Calculate added and deleted lines between the merge base and the head commit
+          TOTAL_CHANGED=$(git diff --numstat "$MERGE_BASE" "$HEAD_SHA" \
+            | awk '{ added += $1; deleted += $2 } END { print added + deleted }')
+
+          # Default to 0 if nothing is output
+          TOTAL_CHANGED=${TOTAL_CHANGED:-0}
+          echo "Total changed lines: $TOTAL_CHANGED"
+
+          # Make the total available for later steps
+          echo "total=$TOTAL_CHANGED" >> "$GITHUB_OUTPUT"
+
+      - name: Fail if too many changes
+        if: ${{ steps.diff_check.outputs.total > 500 }}
+        run: |
+          echo "PR has ${{ steps.diff_check.outputs.total }} changed lines, which exceeds the 500-line limit."
+          echo "Please reduce the size of this PR."
+          exit 1

.github/workflows/stale-prs.yml

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+name: Mark stale PRs
+
+on:
+  schedule:
+    - cron: "0 7 * * *"
+  workflow_dispatch:
+
+permissions:
+  issues: write
+  pull-requests: write
+
+jobs:
+  stale_prs:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/stale@v9
+        with:
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          days-before-stale: 30
+          days-before-close: 15
+          stale-pr-message: "This pull request has been inactive for 30 days. Is it still in progress? If so, please leave a comment or make an update to keep it open. Otherwise, it will be closed automatically in 15 days."
+          close-pr-message: "This pull request was closed automatically due to prolonged inactivity."
+          # Labels
+          stale-pr-label: stalled
+          exempt-draft-pr: true
+          # Do not touch issues
+          days-before-issue-stale: -1
+          days-before-issue-close: -1