Root task entrypoints: test / lint / typecheck / build via uv run

[ulises-jeremias]

Summary

Expose developer commands analogous to npm scripts (build, test, lint, type-check).

CNA mapping

CNA: root package.json scripts + turbo pipelines.

Acceptance criteria

• Documented commands in README and AGENTS.md
• uv run invocations work from repo root
• Optional: [project.scripts] or just docs + Makefile/justfile — pick one and document

Blocked by

none

Blocks

none

Reference

Parity matrix (workspace): knowledge/create-python-app-parity-matrix.md
Reference repo: https://github.com/Create-Node-App/create-node-app

Parent epic

#2