fix: use consistent u32 type for enum constants on Windows

[kajukitli]

bindgen generates enum constants as i32 on Windows MSVC (C standard: enum underlying type is int) but u32 on GCC/Clang when all values are non-negative. This causes type mismatch errors when using the constants.

Add .default_enum_style(bindgen::EnumVariation::Consts) combined with .translate_enum_integer_types(true) to force consistent unsigned types across all platforms.

Fixes errors like:

error[E0308]: mismatched types
   --> ext\node\ops\http2\session.rs:515:33
    |
515 |     if frame.hd.type_ as u32 == ffi::NGHTTP2_PUSH_PROMISE {
    |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^ expected `u32`, found `i32`