Add core docs: README, CONTRIBUTING, Roadmap

[VincentG1234]

Description

The repo is missing basic documentation. We need a minimal setup so people can understand the project and contribute without friction.

Tasks

• README.md

  • what the project does / why it exists
  • quickstart (install + example)
  • link to roadmap + contributing
  • clarify relation to upstream (since this is a fork)

• CONTRIBUTING.md

  • how to run the project locally
  • branch naming (feat/, fix/, etc.)
  • PR expectations (small, clear, tests if relevant)
  • commit style (feat:, fix:, docs:…)

• Roadmap

  • simple structure: Now / Next / Later
  • main priorities (stability, CI, tests, core features)

Done when

• README is enough to get started quickly
• CONTRIBUTING is usable without asking questions
• roadmap is visible and clear
• links between docs are consistent