Add Helm smoke test workflow

- Introduce a GitHub Actions workflow for DevLake Helm chart smoke testing.
- Set up a temporary Kubernetes cluster with kind, install the Helm chart, and verify core services.
- Incorporate health checks for Grafana and connected MySQL datasource.
- Provide detailed diagnostics on failure to assist troubleshooting.

Signed-off-by: kahirokunn <okinakahiro@gmail.com>

Author: kahirokunn

.github/workflows/smoke-test.yml

@@ -0,0 +1,47 @@
+name: DevLake Helm Smoke Test
+
+on:
+  push:
+    branches: [ "**" ]
+  pull_request:
+    branches: [ "**" ]
+
+jobs:
+  smoke-test:
+    name: Smoke Test
+    runs-on: ubuntu-latest
+    timeout-minutes: 45
+    env:
+      RELEASE_NAME: devlake
+      NAMESPACE: devlake
+      GRAFANA_ADMIN_PASSWORD: admin
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v5
+
+      - name: Set up Helm
+        uses: azure/setup-helm@v4
+
+      - name: Create kind cluster
+        uses: helm/kind-action@v1.12.0
+        with:
+          cluster_name: devlake-e2e
+
+      - name: Set up kubectl
+        uses: azure/setup-kubectl@v4
+
+      - name: Build chart dependencies (local)
+        run: |
+          helm dependency build charts/devlake
+
+      - name: Install DevLake chart (with Grafana)
+        run: |
+          ENCRYPTION_SECRET=$(openssl rand -base64 2000 | tr -dc 'A-Z' | fold -w 128 | head -n 1)
+          set -euo pipefail
+          helm install "$RELEASE_NAME" ./charts/devlake \
+            --namespace "$NAMESPACE" \
+            --create-namespace \
+            --wait \
+            --timeout 25m \
+            --set lake.encryptionSecret.secret="${ENCRYPTION_SECRET}" \
+            --set grafana.adminPassword="${GRAFANA_ADMIN_PASSWORD}"