docs: professional README + CONTRIBUTING, CHANGELOG, issue/PR templates

- README rewritten with hero block, feature table, mermaid sequence
  diagram of the discovery flow, FAQ, compatibility matrix, roadmap,
  badges (npm version/downloads, CI, license, TS, PRs welcome).
- CONTRIBUTING.md documents project philosophy, dev setup, PR
  checklist, and release process.
- CHANGELOG.md follows Keep a Changelog 1.1.0; v0.1.0 entry recorded.
- Issue templates: bug report (yml form) + feature request (yml form)
  + config.yml that disables blank issues and links to upstream docs.
- PULL_REQUEST_TEMPLATE.md with checklist matching CONTRIBUTING.
- dependabot.yml for weekly npm + github-actions updates.
- Drop accidental self-dependency added by an earlier 'npm link'.