Skip the nb[3] check when ne[3] == 1, the shader never reads it for a
single stream. Cache views carry the full-buffer stride there, so the old
check reduced to n_kv == kv_size and the path only engaged with the
cache full.
* vulkan : dequant q8_0 KV once in coopmat1
Assisted-by: Claude (Opus 4.8)
* vulkan : fall back instead of aborting when FA scratch exceeds maxStorageBufferRange
* vulkan : require KV-cache layout in FA dequant path
Assisted-by: Claude (Opus 4.8)
* vulkan : skip FA dequant path on coopmat2
Assisted-by: Claude (Opus 4.8)
* tests : add contiguously-allocated quant K/V FA tests
Assisted-by: Claude (Opus 4.8)
* vulkan : trim comments
* vulkan : tighten permutation checks for FA path
* vulkan : set prealloc_x_need_sync after the FA dispatch
* vulkan : exclude Intel Xe1 from FA dequant path
Nathan Wilson