Add Zig bindings for webview, PHP extensions, and libui-ng

[happystraw]

• happystraw/zig-webview - Zig bindings for webview/webview — a tiny cross-platform library for building desktop applications with web technologies using a native browser widget.
• happystraw/phpz - Build PHP Extensions with Zig (A Zig framework for building PHP extensions with PHP C API bindings.)
• libui-ng - Zig Build System for libui-ng: a portable GUI library for C. "libui for the next generation"

[gemini-code-assist]

Code Review

This pull request adds three new entries to the README.md: zig-webview under GUI frameworks, phpz under FFI bindings, and libui-ng under projects that have replaced their build systems with Zig. Review feedback suggests simplifying the description for phpz to avoid redundancy and reformatting the libui-ng entry to better match the established style of the section.