Reconciles the handoff and ledger against a main that advanced past
this branch's base: the header, `main` anchor, and canonical-base
description take main's richer versions restamped to 74301d1, main's
new PTY-terminate lane is kept alongside the Lean lane, and main's
Stage 4a/rev-8 lane history is dropped in favour of the Stage 4b lane
that supersedes it — per this ledger's own rule to remove entries when
their PR merges.
Also fixes the coherence census's second count, which still said eight
settings three paragraphs below the nine it now lists.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011LFvC4FQtux4y32KuevZ7B