## Summary

Every component in the toolkit now ships a README that follows the same
structure used by well-known PHP libraries like Guzzle, Flysystem, and
Symfony Console:

- **Description** — what the component does and why you'd reach for it
- **Installation** — the `composer require` one-liner
- **Quick Start** — a minimal working example you can copy-paste
- **Usage** — subsections for each major feature, with real code
examples derived from the component's own test suite
- **API Reference** — tables of key classes and methods
- **Requirements** — PHP version and dependency info

The 16 components that had no README now have one. The 2 that already
had one (HttpClient, CORSProxy) have been rewritten with the same depth
and structure.

All examples use PHP 7.2-compatible syntax and follow WordPress coding
style (spaces inside parentheses, `$snake_case` variables,
`snake_case()` methods).

## Test plan

- [ ] Verify each README renders correctly on GitHub
- [ ] Spot-check code examples against actual component APIs
- [ ] Confirm no PHP 7.2+ incompatible syntax in examples