fix: pcie gen, nccl binary, netconf sudo, boot noise, firmware cleanup

- nvidia collector: read pcie.link.gen.current/max from nvidia-smi instead
  of sysfs to avoid false Gen1 readings when GPU is in ASPM idle state
- build: remove bee-nccl-gpu-stress from rm -f list so shell script from
  overlay is not silently dropped from the ISO
- smoketest: add explicit checks for bee-gpu-burn, bee-john-gpu-stress,
  bee-nccl-gpu-stress, all_reduce_perf
- netconf: re-exec via sudo when not root to fix RTNETLINK/resolv.conf errors
- auto/config: reduce loglevel 7→3 to show clean systemd output on boot
- auto/config: blacklist snd_hda_intel and related audio modules (unused on servers)
- package-lists: remove firmware-intel-sound and firmware-amd-graphics from
  base list; move firmware-amd-graphics to bee-amd variant only
- bible-local: mark memtest ADR resolved, document working solution

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

iso/builder/auto/config

@@ -32,7 +32,7 @@ lb config noauto \
     --memtest memtest86+ \
     --iso-volume "EASY_BEE_${BEE_GPU_VENDOR_UPPER:-NVIDIA}" \
     --iso-application "EASY-BEE-${BEE_GPU_VENDOR_UPPER:-NVIDIA}" \
-    --bootappend-live "boot=live components video=1920x1080 console=tty0 console=ttyS0,115200n8 loglevel=7 username=bee user-fullname=Bee modprobe.blacklist=nouveau" \
+    --bootappend-live "boot=live components video=1920x1080 console=tty0 console=ttyS0,115200n8 loglevel=3 username=bee user-fullname=Bee modprobe.blacklist=nouveau,snd_hda_intel,snd_hda_codec_realtek,snd_hda_codec_generic,soundcore" \
     --apt-recommends false \
     --chroot-squashfs-compression-type zstd \
     "${@}"