feat: build test-capable image, run tests, then build production image

Dockerfile

@@ -26,7 +26,28 @@ RUN DATABASE_URL="postgresql://user:pass@localhost:5432/dummy" npx prisma genera
 ARG GIT_COMMIT=unknown
 RUN DATABASE_URL="postgresql://user:pass@localhost:5432/dummy" NEXT_PUBLIC_GIT_COMMIT=$GIT_COMMIT npm run build
 
-# Stage 2: Runner
+# Stage 2: Test runner (includes dev dependencies for testing)
+FROM node:20-alpine AS test-runner
+
+# Install dependencies
+RUN apk add --no-cache python3 make g++ git
+
+# Set working directory
+WORKDIR /app
+
+# Copy package files
+COPY package*.json ./
+
+# Install ALL dependencies (including dev dependencies for testing)
+RUN npm ci
+
+# Copy source code
+COPY . .
+
+# Generate Prisma client
+RUN DATABASE_URL="postgresql://user:pass@localhost:5432/dummy" npx prisma generate
+
+# Stage 3: Production runner
 FROM node:20-alpine AS runner
 
 # Install dumb-init for proper signal handling