chore: add Lint action

Author: peku33

.github/workflows/lint.yml

@@ -0,0 +1,50 @@
+name: Lint
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v6
+
+      - name: Set up Python
+        uses: actions/setup-python@v6
+        with:
+          python-version: "3.13"
+          cache: "poetry"
+
+      - name: Install Poetry
+        uses: snok/install-poetry@v1
+        with:
+          virtualenvs-create: true
+          virtualenvs-in-project: true
+          installer-parallel: true
+
+      - name: Install dependencies
+        run: |
+          poetry install --no-interaction --no-root
+
+      - name: Run black
+        run: |
+          poetry run black --check app
+
+      - name: Run isort
+        run: |
+          poetry run isort --check-only app
+
+      - name: Run flake8
+        run: |
+          poetry run flake8 app
+
+      - name: Run mypy
+        run: |
+          poetry run mypy app
+
+      - name: Run pylint
+        run: |
+          poetry run pylint app