feat(iso): add rocm-bandwidth-test for AMD GPU burn-in

- Add rocm-bandwidth-test package to ISO
- Add bee user to 'render' group (/dev/kfd, /dev/dri/renderD* access)
- Add rocm-bandwidth-test symlink alongside rocm-smi

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

iso/builder/config/package-lists/bee.list.chroot

@@ -77,6 +77,8 @@ datacenter-gpu-manager=1:%%DCGM_VERSION%%
 
 # AMD ROCm SMI — GPU monitoring for Instinct cards (repo: rocm/apt/6.3.4 jammy)
 rocm-smi-lib=%%ROCM_SMI_VERSION%%
+# AMD ROCm bandwidth test — used for GPU burn-in stress
+rocm-bandwidth-test=%%ROCM_BANDWIDTH_TEST_VERSION%%
 
 # glibc compat helpers (for any external binaries that need it)
 libc6