chore: add .github workflows

.github/workflows/auto-assign.yml

@@ -0,0 +1,19 @@
+name: Auto Assign
+on:
+  issues:
+    types: [opened]
+  pull_request:
+    types: [opened]
+jobs:
+  run:
+    runs-on: ubuntu-latest
+    permissions:
+      issues: write
+      pull-requests: write
+    steps:
+    - name: 'Auto-assign issue'
+      uses: pozil/auto-assign-issue@v1
+      with:
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          assignees: hongxuchen
+          numOfAssignee: 1

.github/workflows/proof-html.yml

@@ -0,0 +1,11 @@
+name: Proof HTML
+on:
+  push:
+  workflow_dispatch:
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: anishathalye/proof-html@v1.1.0
+        with:
+          directory: ./