Add lint/format/type-check CI job

New "lint" job in validate.yml runs ruff format --check, ruff check,
and ty check against custom_components/ and tests/ on the same
push/PR/schedule triggers as the existing hassfest/hacs/pytest jobs.

.github/workflows/validate.yml

@@ -36,6 +36,32 @@ jobs:
         with:
           category: integration
 
+  lint:
+    name: Lint, format, and type check
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout the repository
+        uses: actions/checkout@v7
+
+      - name: Set up Python
+        uses: actions/setup-python@v7
+        with:
+          python-version: "3.14"
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r requirements-dev.txt
+
+      - name: Run ruff format check
+        run: ruff format --check custom_components tests
+
+      - name: Run ruff lint
+        run: ruff check custom_components tests
+
+      - name: Run ty type check
+        run: ty check custom_components tests
+
   tests:
     name: Pytest
     runs-on: ubuntu-latest