feat: API Gateway (Express 5 + Prisma + Monday) y conexion de apps al API

- api-gateway: servicio Monday (retry 429/complejidad, paginacion cursor,
  column IDs por titulo), endpoints unidades/cotizaciones/clientes/planes,
  webhook con handshake challenge, Prisma SQLite dev, 55 tests
- cotizador: inventario desde /api/unidades con fallback a seed
- alta-clientes: POST /api/clientes + upload multipart de documentos
- cobranza: persistencia via API con respaldo offline en localStorage
- .env.example con board IDs del workspace Frasa-CAS

api-gateway/Dockerfile

@@ -0,0 +1,28 @@
+# ---- Build ----
+FROM node:22-alpine AS build
+WORKDIR /app
+
+COPY package.json package-lock.json ./
+COPY prisma ./prisma
+RUN npm ci
+
+COPY tsconfig.json ./
+COPY src ./src
+RUN npx prisma generate && npm run build
+
+# ---- Runner ----
+FROM node:22-alpine AS runner
+WORKDIR /app
+ENV NODE_ENV=production
+
+COPY package.json package-lock.json ./
+COPY prisma ./prisma
+RUN npm ci --omit=dev
+
+COPY --from=build /app/node_modules/.prisma ./node_modules/.prisma
+COPY --from=build /app/node_modules/@prisma/client ./node_modules/@prisma/client
+COPY --from=build /app/dist ./dist
+
+EXPOSE 3000
+# Aplica migraciones pendientes antes de arrancar
+CMD ["sh", "-c", "npx prisma migrate deploy && node dist/index.js"]