Ferric core — L0 (portable device/fabric abstraction) + L1 (kernel dispatch), on wgpu.
wgpu gives us one API over WebGPU (browser), Vulkan, Metal, DX12, and GL. This crate wraps it
into a tiny Context and the first real kernel (matmul), written ONCE in WGSL and run on any
fabric. The same source compiles to native (Metal/Vulkan/DX12) and to wasm32 for the browser.
Numerics are validated against a plain-Rust CPU reference so "runs everywhere" also means
"computes the same everywhere".