104 reject f64 gpu kernel

// Test 390_104: f64 shapes cannot target the GPU — the capability wall.
//
// Apple GPUs (SPIR-V via MoltenVK) carry no Float64. A `self|mlir[gpu]` op on
// an f64 shape must die loudly at the koru level (KORU123) naming the
// constraint — never lower to a blob that fails downstream or silently
// degrades. First concrete instance of the capability lattice: the compiler
// knows what the target can carry, and says so.

import std/kernel
import std/io

std/kernel:shape(Body) {
    mass: f64,
}

std/kernel:init(Body) {
    { mass: 1.0 },
    { mass: 2.0 },
    { mass: 3.0 },
}
| kernel k |> std/kernel:self|mlir[gpu] { k.mass *= 2.0 }
| computed c |> std/io:print.blk {
        mass[0]={{ c[0].mass:f }} mass[1]={{ c[1].mass:f }} mass[2]={{ c[2].mass:f }}
    }