Initial project setup: Next.js frontend + .NET 9 backend

- Frontend: Next.js 16 + shadcn/ui + Tailwind CSS 4
- Backend: .NET 9 Web API with Npgsql health check
- Docker Compose for prod and dev environments
- Woodpecker CI pipeline for auto-deploy
- Health check endpoints for E2E testing

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/Dockerfile

@@ -0,0 +1,19 @@
+FROM node:20-alpine AS deps
+WORKDIR /app
+COPY package.json package-lock.json ./
+RUN npm ci
+
+FROM node:20-alpine AS builder
+WORKDIR /app
+COPY --from=deps /app/node_modules ./node_modules
+COPY . .
+RUN npm run build
+
+FROM node:20-alpine AS runner
+WORKDIR /app
+ENV NODE_ENV=production
+COPY --from=builder /app/.next/standalone ./
+COPY --from=builder /app/.next/static ./.next/static
+COPY --from=builder /app/public ./public
+EXPOSE 3000
+CMD ["node", "server.js"]