Add CI/CD: Gitea Actions workflows + Act Runner

- .gitea/workflows/test.yml: unit tests + build on every push
- .gitea/workflows/deploy.yml: auto deploy to production on push to main
- .gitea/workflows/preview.yml: PR preview environments at pr-{id}.oil.oci.euphon.net
  - Bakes production DB copy into preview image (no PVC needed)
  - Auto-creates namespace + deployment + ingress with TLS
  - Comments PR with preview URL
  - Tears down on PR close
- scripts/setup-runner.sh: act_runner installation script

Runner: hera-runner (host mode, ubuntu-latest label)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/deploy.yml

@@ -0,0 +1,23 @@
+name: Deploy Production
+on:
+  push:
+    branches: [main]
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Unit tests
+        run: cd frontend && npm ci && npm run test:unit
+
+      - name: Build & Deploy
+        run: |
+          rsync -az --exclude node_modules --exclude .git --exclude .venv . oci:~/oil-calculator/
+          ssh oci "
+            cd ~/oil-calculator &&
+            docker build -t registry.oci.euphon.net/oil-calculator:latest . &&
+            docker push registry.oci.euphon.net/oil-calculator:latest &&
+            sudo k3s kubectl rollout restart deploy/oil-calculator -n oil-calculator
+          "

.gitea/workflows/preview.yml

@@ -0,0 +1,190 @@
+name: PR Preview
+on:
+  pull_request:
+    types: [opened, synchronize, reopened, closed]
+
+env:
+  REGISTRY: registry.oci.euphon.net
+  BASE_DOMAIN: oil.oci.euphon.net
+
+jobs:
+  deploy-preview:
+    if: github.event.action != 'closed'
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Unit tests
+        run: cd frontend && npm ci && npm run test:unit
+
+      - name: Deploy Preview Environment
+        run: |
+          PR_ID="${{ github.event.pull_request.number }}"
+          NS="oil-pr-${PR_ID}"
+          HOST="pr-${PR_ID}.${BASE_DOMAIN}"
+          IMAGE="${REGISTRY}/oil-calculator:pr-${PR_ID}"
+
+          # Sync source to oci build server
+          rsync -az --exclude node_modules --exclude .git --exclude .venv \
+            . oci:/tmp/oil-pr-${PR_ID}-build/
+
+          ssh oci bash -s "${PR_ID}" "${NS}" "${HOST}" "${IMAGE}" << 'DEPLOY_SCRIPT'
+            set -e
+            PR_ID="$1"; NS="$2"; HOST="$3"; IMAGE="$4"
+
+            cd /tmp/oil-pr-${PR_ID}-build
+
+            # Copy production DB into build context so it's baked into image
+            PROD_POD=$(sudo k3s kubectl get pods -n oil-calculator -l app=oil-calculator \
+              --field-selector=status.phase=Running -o jsonpath='{.items[0].metadata.name}' 2>/dev/null || echo "")
+            if [ -n "$PROD_POD" ]; then
+              sudo k3s kubectl cp "oil-calculator/${PROD_POD}:/data/oil_calculator.db" /tmp/pr-${PR_ID}.db
+              mkdir -p data
+              cp /tmp/pr-${PR_ID}.db data/oil_calculator.db
+            fi
+
+            # Build image (with DB baked in)
+            cat > Dockerfile.preview << 'DEOF'
+            FROM node:20-slim AS frontend-build
+            WORKDIR /build
+            COPY frontend/package.json frontend/package-lock.json ./
+            RUN npm ci
+            COPY frontend/ ./
+            RUN npm run build
+
+            FROM python:3.12-slim
+            WORKDIR /app
+            COPY backend/requirements.txt .
+            RUN pip install --no-cache-dir -r requirements.txt
+            COPY backend/ ./backend/
+            COPY --from=frontend-build /build/dist ./frontend/
+            # Bake production DB copy into image
+            COPY data/oil_calculator.db /data/oil_calculator.db
+            ENV DB_PATH=/data/oil_calculator.db
+            ENV FRONTEND_DIR=/app/frontend
+            EXPOSE 8000
+            CMD ["uvicorn", "backend.main:app", "--host", "0.0.0.0", "--port", "8000"]
+            DEOF
+
+            docker build -f Dockerfile.preview -t "${IMAGE}" .
+            docker push "${IMAGE}"
+
+            # Create namespace
+            sudo k3s kubectl create namespace "${NS}" --dry-run=client -o yaml | sudo k3s kubectl apply -f -
+
+            # Copy regcred from production namespace
+            sudo k3s kubectl get secret regcred -n oil-calculator -o json | \
+              sed "s/\"namespace\":\"oil-calculator\"/\"namespace\":\"${NS}\"/" | \
+              sudo k3s kubectl apply -f -
+
+            # Deploy pod + service + ingress (no PVC needed, DB is in image)
+            cat << EOYAML | sudo k3s kubectl apply -f -
+          apiVersion: apps/v1
+          kind: Deployment
+          metadata:
+            name: oil-calculator
+            namespace: ${NS}
+          spec:
+            replicas: 1
+            selector:
+              matchLabels:
+                app: oil-calculator
+            template:
+              metadata:
+                labels:
+                  app: oil-calculator
+              spec:
+                imagePullSecrets:
+                  - name: regcred
+                containers:
+                  - name: app
+                    image: ${IMAGE}
+                    ports:
+                      - containerPort: 8000
+                    resources:
+                      requests:
+                        cpu: 50m
+                        memory: 64Mi
+                      limits:
+                        cpu: 500m
+                        memory: 256Mi
+          ---
+          apiVersion: v1
+          kind: Service
+          metadata:
+            name: oil-calculator
+            namespace: ${NS}
+          spec:
+            selector:
+              app: oil-calculator
+            ports:
+              - port: 80
+                targetPort: 8000
+          ---
+          apiVersion: networking.k8s.io/v1
+          kind: Ingress
+          metadata:
+            name: oil-calculator
+            namespace: ${NS}
+            annotations:
+              traefik.ingress.kubernetes.io/router.tls.certresolver: le
+          spec:
+            ingressClassName: traefik
+            tls:
+              - hosts:
+                  - ${HOST}
+            rules:
+              - host: ${HOST}
+                http:
+                  paths:
+                    - path: /
+                      pathType: Prefix
+                      backend:
+                        service:
+                          name: oil-calculator
+                          port:
+                            number: 80
+          EOYAML
+
+            # Wait for rollout
+            sudo k3s kubectl rollout status deploy/oil-calculator -n "${NS}" --timeout=120s
+
+            # Cleanup build dir
+            rm -rf /tmp/oil-pr-${PR_ID}-build /tmp/pr-${PR_ID}.db
+
+            echo "Preview deployed: https://${HOST}"
+          DEPLOY_SCRIPT
+
+      - name: Comment PR with preview URL
+        run: |
+          PR_ID="${{ github.event.pull_request.number }}"
+          HOST="pr-${PR_ID}.${BASE_DOMAIN}"
+          curl -s -X POST \
+            "https://git.euphon.cloud/api/v1/repos/${{ github.repository }}/issues/${PR_ID}/comments" \
+            -H "Authorization: token ${{ secrets.GITEA_TOKEN }}" \
+            -H "Content-Type: application/json" \
+            -d "{\"body\": \"🚀 Preview deployed: https://${HOST}\n\nDB is a copy of production. Changes here won't affect prod.\"}"
+
+  teardown-preview:
+    if: github.event.action == 'closed'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Teardown Preview Environment
+        run: |
+          PR_ID="${{ github.event.pull_request.number }}"
+          NS="oil-pr-${PR_ID}"
+          IMAGE="${REGISTRY}/oil-calculator:pr-${PR_ID}"
+
+          ssh oci "
+            sudo k3s kubectl delete namespace ${NS} --ignore-not-found
+            docker rmi ${IMAGE} 2>/dev/null || true
+          "
+
+      - name: Comment PR
+        run: |
+          PR_ID="${{ github.event.pull_request.number }}"
+          curl -s -X POST \
+            "https://git.euphon.cloud/api/v1/repos/${{ github.repository }}/issues/${PR_ID}/comments" \
+            -H "Authorization: token ${{ secrets.GITEA_TOKEN }}" \
+            -H "Content-Type: application/json" \
+            -d "{\"body\": \"🗑️ Preview environment torn down.\"}"

.gitea/workflows/test.yml

@@ -0,0 +1,17 @@
+name: Test
+on: [push]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install dependencies
+        run: cd frontend && npm ci
+
+      - name: Unit tests
+        run: cd frontend && npm run test:unit
+
+      - name: Build check
+        run: cd frontend && npm run build