feat(amd): first-class R9700 (gfx1201/RDNA4) support for Qwen3.6-27B

[DeanoC]

Summary

Makes the AMD Radeon AI PRO R9700 (gfx1201, RDNA4 / Navi 48) a first-class AMD target for the DFlash Qwen3.6-27B stack.

The HIP build pipeline compiled RDNA4 as gfx1200 (Navi 44, RX 9060-class) and mislabeled it "RX 9070". The R9700 is gfx1201, which is not code-object compatible with gfx1200 — so the published :rocm image and the documented build produced no native R9700 kernels (ggml-hip fails to load / falls back badly on the R9700).

Changes

• Build matrix: add gfx1201 to the default fat-binary HIP arch list in docker-bake.hcl, Dockerfile.rocm, and the CI main/release matrix (.github/workflows/docker.yml). PR builds stay gfx1151-only for fast CI. Corrected the RDNA4 labels (gfx1200 = RX 9060, gfx1201 = RX 9070 / R9700) and noted the code-object incompatibility.
• rocWMMA validation on AMD: test_flashprefill_kernels (the Phase 2 flashprefill numerics test) now builds under HIP too — it was CUDA-only, so there was previously no way to validate the rocWMMA path on AMD. The CUDA-spelled test compiles via the existing hip_compat/ shim.
• Docs: R9700 row in the README "Tested Machines" table; gfx1201 build + --ddtree-budget=22 tuning, the new HIP numerics test, and multi-GPU / Fedora-PIE build notes in server/README.md.

No kernel changes: ROCm 7.1's rocWMMA handles the gfx12 WMMA operand-format change internally.

Validation — real R9700 (gfx1201, ROCm 7.1.1)

Native gfx1201 build (Phase 1 + Phase 2 rocWMMA); the built libggml-hip.so contains native hipv4-amdgcn-amd-amdhsa--gfx1201 code objects.

Check	Result
test_server_unit	1984 assertions, 0 failures
test_flashprefill_kernels (rocWMMA)	PASS — max diff 5e-4; e2e flash_prefill_forward_bf16 @ S=8192 = 10.7 ms/iter
Qwen3.6-27B Q4_K_M + DFlash, --ddtree-budget=22	54.65 tok/s mean decode (bench_he.py --n-gen 256, AL 7.14, range 36.9–93.0 tok/s)
16K-context generation	coherent

Notes

• Validated on a box with the R9700 (gfx1201);
• Fedora's system ROCm lives under /usr and links PIE by default; the local build used -DCMAKE_HIP_COMPILER_ROCM_ROOT=/usr -DROCM_PATH=/usr -DCMAKE_EXE_LINKER_FLAGS=-no-pie (documented in server/README.md). The Ubuntu-based Dockerfile.rocm is unaffected.

[DeanoC]

Closing as obsolete: the equivalent upstream PR Luce-Org#435 was merged, and this fork main has now been synced with upstream main.