fix: audit pipeline correctness after full review

- bee-audit init.d: use --output file: so "audit output written" is logged
  (stdout mode silently redirects, never emits the slog confirmation)
- build-nvidia-module.sh: use $KERNEL_SRC in find for .ko collection
  (was hardcoded $EXTRACT_DIR/kernel, silent failure if path differs)
- smoketest: add bee-audit to required services (was never checked)
- smoketest: remove legacy bee-audit-debug from service list
- smoketest: internet ping → warn (live CD runs in isolated network, no internet)
- build.sh: auto-copy smoketest.sh → overlay/usr/local/bin/bee-smoketest
  (removes manual sync hazard; smoketest.sh is now single source of truth)
- remove static overlay/usr/local/bin/bee-smoketest (generated by build.sh now)

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

iso/overlay/etc/init.d/bee-audit

@@ -9,7 +9,7 @@ depend() {
 
 start() {
     ebegin "Running hardware audit"
-    /usr/local/bin/audit --output stdout > /var/log/bee-audit.json 2>/var/log/bee-audit.log
+    /usr/local/bin/audit --output "file:/var/log/bee-audit.json" 2>/var/log/bee-audit.log
     local rc=$?
     if [ $rc -eq 0 ]; then
         einfo "Audit complete: /var/log/bee-audit.json"