docs(readme): content parity - ecosystem, documentation, features, current versions

[rennf93]

Content parity for the README body: the Ecosystem section now covers all six families (Python, Go, PHP, TypeScript, Rust, AI Coding Agents) with correct package names and live version badges (the Rust rows no longer claim placeholder status), the Documentation section links the package's docs site, the engine and adapter Features sections state the shipped capability set, and stale version claims in Install/Status lines are refreshed to the released train. README-only change.

[github-actions]

Thanks for opening your first pull request on flaskapi-guard!

Quick checklist before review (most of these are enforced by CI, but worth a glance):

• make lint — ruff format, ruff check, mypy, and vulture
• make test (or make local-test) — full test suite passes with 100% coverage
• make security — bandit, safety, and pip-audit all clean
• make quality — radon and xenon complexity thresholds respected
• No # noqa / # type: ignore shortcuts; pre-existing violations in touched files are fixed
• Added an entry under ## Unreleased in CHANGELOG.md
• If you touched a public API, updated the relevant page under docs/
• If the change involves engine logic, the corresponding fix landed in guard-core first

See CONTRIBUTING.md for the full workflow and the Code of Conduct for the community standards we follow.

Welcome aboard — a maintainer will review shortly.