Release v0.2.5 — security fix: HTTP response splitting

The uopz header() override didn't reject CRLF/NUL in values, breaking
PHP's native protection (in place since 4.4.2). User-controlled input
passed to header() / setcookie() / redirect() could smuggle additional
response headers, enabling session fixation and cache poisoning.

All entry points patched:
- header(), Response::header()
- Response::redirect()
- setcookie(), setrawcookie()

Cookie name char-class rules now match PHP native setcookie.
9 new regression tests added.

All v0.2.x releases prior to v0.2.5 are affected. Upgrade recommended.