fix: pre-landing review round — 8 auto-fixes + 8 accepted findings hardened

The ship review army (4 specialists + red-team + checklist, 29 findings)
produced 8 mechanical auto-fixes and 11 decisions; the accepted set:

- win32 slug parity completed: lib/bin-context.ts gains the remote-first
  outermost walk + degraded-cache self-heal the bash side got this wave —
  the two implementations now agree on the stray-marker live-bug shape,
  pinned by shared fixtures (multi-specialist 9/10 finding).
- probe honors the plan's bounded-read decision: 256KB prefix, extraction
  semantics mirrored from parseTranscriptJsonl so probe/prepare can never
  diverge on the same file (>1MB transcript test).
- policy normalize parity: bash normalize() now matches canonicalizeRemote
  on .git/-trailing and uppercase-.GIT shapes (7-shape corpus pinned two
  ways) — a deny for those shapes could previously slip the transcript gate.
- session-update reclaim is TOCTOU-safe (atomic mv-aside on both branches).
- settings-hook: unparseable settings.json errors instead of being replaced
  with {}; ensure-event keys on (event, source) so matcher changes update
  in place — never zero or two registrations.
- dot-only slug guard at both parse sites (hostile 'url = ..' can't escape
  projects/); enqueue tmp-file janitor (1h TTL, inside the drain lock);
  brain-sync .migrating never clobbered; drop-queue/status count .migrating;
  snapshot -o warning correct + surfaced in diff mode; version-bump test
  order-dependence removed; uninstall clears the advance stamp.

Deferred with record: slug heal-probe cost sentinel (P3 TODO), FF_OK
conflation (noted, misdiagnosis-only).

270 pass / 0 fail across the 10 touched suites.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

bin/gstack-brain-uninstall

@@ -23,6 +23,7 @@
 #   .brain-queue.jsonl         — legacy pending queue (pre-spool)
 #   .brain-discover-cursor     — discover-new cursor
 #   .brain-last-push           — timestamp marker
+#   .brain-worktree-last-advance — daily worktree-advance stamp (#2516)
 #   .brain-skip.txt            — user-maintained skip list
 #   .brain-sync.lock.d/        — lock dir (if present)
 #   .brain-sync-status.json    — health status
@@ -125,6 +126,7 @@ rm -f "$GSTACK_HOME/.brain-queue.jsonl.migrating" 2>/dev/null || true
 rm -f "$GSTACK_HOME/.brain-discover-cursor" 2>/dev/null || true
 rm -f "$GSTACK_HOME/.brain-last-push" 2>/dev/null || true
 rm -f "$GSTACK_HOME/.brain-last-pull" 2>/dev/null || true
+rm -f "$GSTACK_HOME/.brain-worktree-last-advance" 2>/dev/null || true
 rm -f "$GSTACK_HOME/.brain-skip.txt" 2>/dev/null || true
 rm -f "$GSTACK_HOME/.brain-sync-status.json" 2>/dev/null || true
 rm -rf "$GSTACK_HOME/.brain-sync.lock.d" 2>/dev/null || true