Refactor duplicate expect() calls in SPIR-V binary emitter

[Apocky]

Summary

cssl-cgen-gpu-spirv/src/binary_emit.rs has 7 near-identical .expect() calls:

let parsed = dr::load_words(&words).expect("rspirv must parse emitted binary");

These appear at lines ~394, 409, 442, 475, 499, 519, 539 — one per SPIR-V test case. They all do the same thing (round-trip the emitted binary through rspirv's parser) but give no context about which operation failed.

What to do

1. Extract a helper function:

   fn roundtrip(words: &[u32], ctx: &str) -> dr::Module {
       dr::load_words(words).unwrap_or_else(|e| panic!("rspirv parse failed in {ctx}: {e}"))
   }

2. Replace all 7 call sites with roundtrip(&words, "sphere_sdf_forward") etc.

Why this is a good first issue

• Self-contained change in a single file
• No type system or IR knowledge needed
• Teaches the SPIR-V codegen crate layout
• Improves debuggability when a future backend change breaks round-trip

Files

• compiler-rs/crates/cssl-cgen-gpu-spirv/src/binary_emit.rs