Add frontend service to Docker setup and configure networking

Introduced a new `frontend` service in `docker-compose.yml`, complete with build, healthchecks, and networking. Added a multi-stage Dockerfile for the frontend, a `.dockerignore` file, and a startup script to wait for the backend. Updated Next.js configuration for Docker compatibility and added API type definitions.

frontend/Dockerfile

@@ -0,0 +1,36 @@
+# Stage 1: Dependencies
+FROM node:20-alpine AS deps
+WORKDIR /app
+COPY package.json package-lock.json ./
+RUN npm ci
+
+# Stage 2: Builder
+FROM node:20-alpine AS builder
+WORKDIR /app
+COPY --from=deps /app/node_modules ./node_modules
+COPY . .
+ENV NEXT_TELEMETRY_DISABLED 1
+RUN npm run build
+
+# Stage 3: Runner
+FROM node:20-alpine AS runner
+WORKDIR /app
+
+ENV NODE_ENV production
+ENV NEXT_TELEMETRY_DISABLED 1
+
+RUN addgroup --system --gid 1001 nodejs
+RUN adduser --system --uid 1001 nextjs
+
+COPY --from=builder /app/public ./public
+COPY --from=builder /app/.next/standalone ./
+COPY --from=builder /app/.next/static ./.next/static
+
+USER nextjs
+
+EXPOSE 3000
+
+ENV PORT 3000
+ENV HOSTNAME "0.0.0.0"
+
+CMD ["node", "server.js"]