Remove AMD ROCm support — CPU and NVIDIA only

BREAKING: Remove Dockerfile.rocm, compose.rocm.yaml, and ROCm image
build/push from the release pipeline. Remove AMD quick-start and ROCm
references from README and DEVELOPER docs. Update docker-deployment
and developer-docs specs to reflect CPU + NVIDIA only.

The ROCm variant added significant complexity (4.2GB torch wheel,
>20GB container) with limited usage. Users on AMD GPUs should stay
on engine v3.2.x or switch to CPU mode.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

release-engine.sh

@@ -151,14 +151,11 @@ fi
 echo "==> Building Docker engine images ($VERSION)"
 
 NVIDIA_IMAGE="${IMAGE_BASE}/engine:${DOCKER_TAG}-nvidia"
-ROCM_IMAGE="${IMAGE_BASE}/engine:${DOCKER_TAG}-rocm"
 CPU_IMAGE="${IMAGE_BASE}/engine:${DOCKER_TAG}-cpu"
 NVIDIA_LATEST="${IMAGE_BASE}/engine:latest-nvidia"
-ROCM_LATEST="${IMAGE_BASE}/engine:latest-rocm"
 CPU_LATEST="${IMAGE_BASE}/engine:latest-cpu"
 
 run docker build -t "$NVIDIA_IMAGE" -t "$NVIDIA_LATEST" -f "$ENGINE_DIR/Dockerfile.nvidia" "$ENGINE_DIR"
-run docker build -t "$ROCM_IMAGE" -t "$ROCM_LATEST" -f "$ENGINE_DIR/Dockerfile.rocm" "$ENGINE_DIR"
 run docker build -t "$CPU_IMAGE" -t "$CPU_LATEST" -f "$ENGINE_DIR/Dockerfile.cpu" "$ENGINE_DIR"
 
 echo ""
@@ -207,9 +204,6 @@ RELEASE_NOTES="## Docker images
 # NVIDIA GPU
 docker pull ${NVIDIA_IMAGE}
 
-# AMD GPU (ROCm)
-docker pull ${ROCM_IMAGE}
-
 # CPU only
 docker pull ${CPU_IMAGE}
 \`\`\`
@@ -241,8 +235,6 @@ echo "==> Pushing Docker images to $REGISTRY"
 
 run docker push "$NVIDIA_IMAGE"
 run docker push "$NVIDIA_LATEST"
-run docker push "$ROCM_IMAGE"
-run docker push "$ROCM_LATEST"
 run docker push "$CPU_IMAGE"
 run docker push "$CPU_LATEST"
 
@@ -256,7 +248,6 @@ echo "==> Release $GIT_TAG complete!"
 echo ""
 echo "    Images:"
 echo "      $NVIDIA_IMAGE"
-echo "      $ROCM_IMAGE"
 echo "      $CPU_IMAGE"
 if [[ -n "${MCP_IMAGE:-}" ]]; then
     echo "      $MCP_IMAGE"