Add build workflow

.github/workflows/build.yml

@@ -0,0 +1,25 @@
+name: Build
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.10'
+      - name: Install ESPHome
+        run: |
+          python3 -m venv venv
+          source venv/bin/activate
+          pip3 install wheel esphome
+      - name: Build firmware
+        run: venv/bin/esphome compile esphome/config.yaml