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/build.sh

@@ -862,7 +862,6 @@ rm -f \
     "${OVERLAY_STAGE_DIR}/etc/bee-release" \
     "${OVERLAY_STAGE_DIR}/root/.ssh/authorized_keys" \
     "${OVERLAY_STAGE_DIR}/usr/local/bin/bee" \
-    "${OVERLAY_STAGE_DIR}/usr/local/bin/bee-nccl-gpu-stress" \
     "${OVERLAY_STAGE_DIR}/usr/local/bin/john" \
     "${OVERLAY_STAGE_DIR}/usr/local/lib/bee/bee-gpu-burn-worker" \
     "${OVERLAY_STAGE_DIR}/usr/local/bin/bee-smoketest" \