### wai-pack-gpu: the packer's kernels held to integer types on naga's IR

- **packaging §11.6 item 1** forbids running a step on a backend that computes it otherwise than
  its definition, in floating point among them. `wai-pack-gpu/tests/integer_only.rs` now holds
  the motion search, SSE and BLAKE3 kernels, on the IR of naga 30.0.1 (the translator wgpu
  compiles them with), to the first two conditions of determinism-tiers §5, *Claiming the tier
  on a GPU*: each validates with no capability (no `f16`, no 64-bit type, no subgroup or quad
  operation, no extension), and every type, every expression's type and every literal is
  `bool`, `i32` or `u32`. The kernels it checks are every `.wgsl` file the crate holds, and each
  is the text the crate compiles. Six planted violations (a floating-point value, vector,
  built-in and bitcast, `f16`, a subgroup reduction) are each refused by the rule they break.
- It needs no adapter. `wai-pack.yml` runs it on the macOS leg, where the crate is built, and
  requires its lines; naga enters as a dev-dependency at the release wgpu already uses, so the
  lockfile gains no package.