Release v0.4.12

- echo/print interleave with yield in streamed generators (wire-order flush).
- ext#55 async-log consumer coroutine leak under coroutine-legacy (ext 0.3.59).
- #443 fork-CGI child streams returned Generator/Closure.
- #453 getallheaders()/apache_request_headers() in CGI subprocess.
- #449 ZEALPHP_MAX_REQUEST=0 disables worker recycle. #442 render() template-dir confinement.
- #459 SERVER_NAME host-only. #455 null-upload parity. #448 get_string_between.
- #444/#446 htmx separate-template + nested-fragment. #458/#454/#457 page-scope isolation.
- docs: PSR table (#451), 4 isolation/exit env knobs (#450), api verb-named gotcha.
- chore: docker PHP 8.5; CI/dev dep bumps.