MODEL-MM-GLM53-FLASH: the compose — glm5_next_device.cpp and the remaining nine arms #3174

Row: MODEL-MM-glm5-next-glm5-next-for-conditional-generation

Glm5NextForConditionalGeneration (GLM-5.3-Flash) has three of eleven arms on a
device queue after W9c-3a (expert GEMM), W9c-2 (KDA recurrence, MoE router
topk), and W9c-3b (KV binding). The other eight still run on the interposed CPU
queue that Glm5NextHostForward constructs at glm5_next_forward.cpp:288. O43
discloses that, and this issue owns the wave that closes it.

Scope

Create glm5_next_device.cpp following kimi_linear_device.cpp's
single-queue, device-resident pattern. Move six arms from host to device where
providers exist on both CUDA and ROCm:

• RMSNorm (vt::RmsNorm)
• Embedding gather (vt::Embedding / vt::EmbeddingQuant)
• Chunked lm_head (vt::Matmul)
• DSA k-pool indexer (vt::Glm5NextKpoolCompress / Select — O36)
• MoE combine (vt::MoeCombine)
• Dense and shared MLPs (vt::Matmul)

Two arms stay as host-fallback islands:

• Eager MLA attention (needs W9c-1's port to mla::ForwardMlaAttentionBlock)
• mHC sites (O34 — kDeepseekV4Mhc has no ROCm provider)

Owed

• W9c-1 (MLA attention onto mla::ForwardMlaAttentionBlock) — REFUSED, owns
  the MLA host-fallback island
• O34 (kDeepseekV4Mhc ROCm provider) — owns the mHC host-fallback island
• O36 (k-pool device ops wired) — DISCHARGED by this wave