refactor(iso): replace chroot hooks for DCGM/ROCm with live-build apt sources

Move datacenter-gpu-manager and rocm-smi-lib from dynamic chroot hooks
into live-build's config/archives mechanism so lb caches the .deb files
in cache/packages.chroot/ between builds, eliminating repeated 900+ MB
downloads. Versions pinned via VERSIONS and substituted into package
lists at build time.

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

iso/builder/build.sh

@@ -337,7 +337,9 @@ sh "${BUILDER_DIR}/build-nccl-tests.sh" \
     "${NCCL_TESTS_VERSION}" \
     "${NCCL_VERSION}" \
     "${NCCL_CUDA_VERSION}" \
-    "${DIST_DIR}"
+    "${DIST_DIR}" \
+    "${NVCC_VERSION}" \
+    "${DEBIAN_VERSION}"
 
 NCCL_TESTS_CACHE="${DIST_DIR}/nccl-tests-${NCCL_TESTS_VERSION}"
 cp "${NCCL_TESTS_CACHE}/bin/all_reduce_perf" "${OVERLAY_STAGE_DIR}/usr/local/bin/all_reduce_perf"
@@ -371,6 +373,14 @@ if [ -f "${OVERLAY_STAGE_DIR}/etc/motd" ]; then
     mv "${OVERLAY_STAGE_DIR}/etc/motd.patched" "${OVERLAY_STAGE_DIR}/etc/motd"
 fi
 
+# --- substitute version placeholders in package list ---
+sed -i \
+    -e "s/%%DCGM_VERSION%%/${DCGM_VERSION}/g" \
+    -e "s/%%ROCM_VERSION%%/${ROCM_VERSION}/g" \
+    -e "s/%%ROCM_SMI_VERSION%%/${ROCM_SMI_VERSION}/g" \
+    "${BUILD_WORK_DIR}/config/package-lists/bee.list.chroot" \
+    "${BUILD_WORK_DIR}/config/archives/rocm.list.chroot"
+
 # --- sync overlay into live-build includes.chroot ---
 LB_DIR="${BUILD_WORK_DIR}"
 LB_INCLUDES="${LB_DIR}/config/includes.chroot"