bookend: land prior part-2 GA-R4 close + dc0-activation part-3 progress (amphora FIXED, LB blocked on v6 overlay) ...

Lands the prior session's savegame residue (GA-R4 part-2 close block in
session-ledger.md, the 2026-08-08 ledger rotation to archive/, and the
dc0-activation-checkpoint queued-findings sweep) which was left uncommitted
pending the operator's push decision (now pushed: a25ed99..a6340e6).

CURRENT-STATE.md gets this session's (part 3) measured status update, which
also clears repo-lint L10 for the docs/audit/ sweep file:
 - amphora build RESOLVED (was part-2 retrofit exit-1 INCIDENT): root cause
   loop-devices-absent-in-LXD + dib-apt-targets-unreachable-public-archive;
   fix = loop passthrough + retrofit ubuntu-mirror -> dc0 mirror. Image
   775ebeba... ACTIVE+tagged octavia-amphora.
 - G18 OWED#3 (o-hm0 MTU) PASS.
 - 1 test LB blocked on geneve-over-v6 overlay (o-hm0->amphora 100% ICMPv6
   loss); UNDER INVESTIGATION (== the verify-live geneve-over-v6 wrap gate).

Revert: git revert this commit (records only; no live cloud state changed by
this commit -- the live mutations are logged for the forthcoming changelog).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Fg98z7QyzwYUs8fsWCn728