add typing-checks workflow

Author: dlqqq

.github/workflows/typing-checks.yml

@@ -0,0 +1,43 @@
+name: Typing Checks
+
+on:
+  push:
+    # IMPORTANT: update these paths when we expand type-checking coverage
+    branches: [main]
+    paths:
+      - 'jupyter_server_documents/rooms/**'
+      - '.github/workflows/typing-checks.yml'
+  pull_request:
+    branches: [main]
+    paths:
+      - 'jupyter_server_documents/rooms/**'
+      - '.github/workflows/typing-checks.yml'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  type-check:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ['3.10', '3.11', '3.12', '3.13']
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Base Setup
+        uses: jupyterlab/maintainer-tools/.github/actions/base-setup@v1
+        with:
+          python_version: ${{ matrix.python-version }}
+
+      - name: Install dependencies
+        run: |
+          python -m pip install mypy
+          python -m pip install -e .[test]
+
+      - name: Type-check `rooms` module
+        run: |
+          mypy jupyter_server_documents/rooms