feat(dcgm): add NVIDIA DCGM diagnostics, fix KVM console

- Add 9002-nvidia-dcgm.hook.chroot: installs datacenter-gpu-manager
  from NVIDIA apt repo during live-build
- Enable nvidia-dcgm.service in chroot setup hook
- Replace bee-gpu-stress with dcgmi diag (levels 1-4) in NVIDIA SAT
- TUI: replace GPU checkbox + duration UI with DCGM level selection
- Remove console=tty2 from boot params: KVM/VGA now shows tty1
  where bee-tui runs, fixing unresponsive console

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

iso/builder/auto/config

@@ -32,6 +32,6 @@ lb config noauto \
     --memtest none \
     --iso-volume "EASY-BEE" \
     --iso-application "EASY-BEE" \
-    --bootappend-live "boot=live components console=tty2 console=ttyS0,115200n8 loglevel=7 username=bee user-fullname=Bee modprobe.blacklist=nouveau" \
+    --bootappend-live "boot=live components console=ttyS0,115200n8 loglevel=7 username=bee user-fullname=Bee modprobe.blacklist=nouveau" \
     --apt-recommends false \
     "${@}"

iso/builder/config/hooks/normal/9000-bee-setup.hook.chroot

@@ -21,6 +21,7 @@ ensure_bee_console_user() {
 ensure_bee_console_user
 
 # Enable bee services
+systemctl enable nvidia-dcgm.service 2>/dev/null || true
 systemctl enable bee-network.service
 systemctl enable bee-nvidia.service
 systemctl enable bee-preflight.service

iso/builder/config/hooks/normal/9002-nvidia-dcgm.hook.chroot

@@ -0,0 +1,66 @@
+#!/bin/sh
+# 9002-nvidia-dcgm.hook.chroot — install NVIDIA DCGM inside the live-build chroot.
+# DCGM (Data Center GPU Manager) provides dcgmi diag for acceptance testing.
+# Adds NVIDIA's CUDA apt repository (debian12/x86_64) and installs datacenter-gpu-manager.
+
+set -e
+
+NVIDIA_KEYRING="/usr/share/keyrings/nvidia-cuda.gpg"
+NVIDIA_LIST="/etc/apt/sources.list.d/nvidia-cuda.list"
+NVIDIA_KEY_URL="https://developer.download.nvidia.com/compute/cuda/repos/debian12/x86_64/3bf863cc.pub"
+NVIDIA_REPO="https://developer.download.nvidia.com/compute/cuda/repos/debian12/x86_64/"
+APT_UPDATED=0
+
+mkdir -p /usr/share/keyrings /etc/apt/sources.list.d
+
+ensure_tool() {
+    tool="$1"
+    pkg="$2"
+    if command -v "${tool}" >/dev/null 2>&1; then
+        return 0
+    fi
+    if [ "${APT_UPDATED}" -eq 0 ]; then
+        apt-get update -qq
+        APT_UPDATED=1
+    fi
+    DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends "${pkg}"
+}
+
+ensure_cert_bundle() {
+    if [ -s /etc/ssl/certs/ca-certificates.crt ]; then
+        return 0
+    fi
+    if [ "${APT_UPDATED}" -eq 0 ]; then
+        apt-get update -qq
+        APT_UPDATED=1
+    fi
+    DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends ca-certificates
+}
+
+if ! ensure_cert_bundle || ! ensure_tool wget wget || ! ensure_tool gpg gpg; then
+    echo "WARN: prerequisites missing — skipping DCGM install"
+    exit 0
+fi
+
+# Download and import NVIDIA GPG key
+if ! wget -qO- "${NVIDIA_KEY_URL}" | gpg --dearmor --yes --output "${NVIDIA_KEYRING}"; then
+    echo "WARN: failed to fetch NVIDIA GPG key — skipping DCGM install"
+    exit 0
+fi
+
+cat > "${NVIDIA_LIST}" <<EOF
+deb [signed-by=${NVIDIA_KEYRING}] ${NVIDIA_REPO} /
+EOF
+
+apt-get update -qq
+
+if DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends datacenter-gpu-manager; then
+    echo "=== DCGM: datacenter-gpu-manager installed ==="
+    dcgmi --version 2>/dev/null || true
+else
+    echo "WARN: datacenter-gpu-manager install failed — DCGM unavailable"
+fi
+
+# Clean up apt lists to keep ISO size down
+rm -f "${NVIDIA_LIST}"
+apt-get clean