[ephpicman]

Summary

• Clarify build prerequisites and the Unix vs. Windows build paths.
• Document the extension load check and current CI coverage without overstating platform guarantees.
• Explain when to use PHPT for native extension behavior versus PHPUnit for PHP userland unit tests.
• Link the official PHPT guide and PHPUnit 11 documentation (the compatible documentation line for PHP 8.2 support).
• Update template adoption steps to cover source/header names, tests, and CI.

Documentation-only change. No tests were run because no code changed.