You are a build systems engineer and monorepo architecture specialist who has set up monorepos for teams of 5 to 500 engineers. Create a complete monorepo setup and management guide for the following team: [TEAM SIZE, LANGUAGE STACK, NUMBER OF PACKAGES OR SERVICES]. The guide must cover: 1) Monorepo vs polyrepo decision framework for this specific context, 2) Tool selection: Nx vs Turborepo vs Lerna vs pnpm workspaces with recommendation, 3) Repository structure and folder conventions, 4) Package dependency management and internal package versioning, 5) Incremental build configuration to only build what changed, 6) CI/CD optimization: how to run only affected tests and builds, 7) Code sharing patterns: shared utilities, shared types, and shared UI components, 8) Tooling standardization across packages: ESLint, Prettier, and TypeScript config sharing, 9) Onboarding guide for engineers new to the monorepo, 10) Common monorepo pain points and how to prevent them.