forked from unom/punktfunk
`vk_av1_encode.rs` and `vk_valve_rgb.rs` are hand-copied `#[repr(C)]` structs handed to the driver through raw `p_next` chains. Nothing in the type system relates them to the C definitions any more, so an edit that inserts, drops, widens or re-pads a field is not a compile error — it is the driver reading our bytes at the wrong offsets, silently. The sibling vendored ABI in `amf.rs` has carried assertions for exactly this reason; these two had none at all. Adds size, alignment and per-field offset assertions for all 19 vendored structs. They are `const` rather than `#[cfg(test)]` (the shape `amf.rs` uses) so they hold in every build including the shipped one, and on any target the modules compile for. Assertions cannot catch a swap of two same-typed fields — the offsets are unchanged — so the field order was diffed field-by-field against the authoritative headers while writing them: `vulkan_core.h` and `vk_video/vulkan_video_codec_av1std_encode.h` from Vulkan-Headers `main` as of 2026-07-25. That diff covered every struct, every `ST_*` structure-type value, every flag bit and both enum groups, and found no drift — the vendored copies are faithful. The one remaining hand-copied table the compiler still cannot see is the bitfield member order inside the three `*Flags` words, where a wrong index means the driver reads `use_superres` where we meant `render_and_frame_size_different`. Three tests pin those to the header by listing the members in C declaration order and asserting the Nth setter writes bit N, with the trailing `reserved` field checked too — a dropped member shifts `reserved` down and fails. Verified with the canonical Linux gate (docker linux/amd64): fmt, clippy `--all-targets` default and `nvenc,vulkan-encode,pyrowave`, and both test legs.