Adds 5.10.4 Round-6 summary section to DRIVER-MANAGER.md covering
N20-E1 (error_channel OOM cap), N20-E2 (6-variant decode), N20-A4
(aer BDF validation), N20-S6 (heartbeat log failures), and N22 (stale
doc removal). Updates last-updated header and test count (164->166).
Removes three orphaned docs that had zero references in the repo
and were last-modified Jul 10-14 vs every other doc Jul 26-27:
BLUETOOTH-IMPLEMENTATION-PLAN.md, CUB-PACKAGE-MANAGER.md, and
USB-VALIDATION-RUNBOOK.md. Backup tarball at
/tmp/opencode/stale-doc-backup-2026-07-27-round18.tar.gz; audit trail
in SUPERSEDED-DOC-LOG.md Round-18 entry.
vasilito
f861f3cfb5