Hub: guide full-text re-push on version bump -> one-line changelog + GET /guide pull (524 msgs/4.9MB per 11d, 69% of hub bytes)

monitor-llmmsgsrv-cc audit 2026-08-22 (/resource/llmmsg-srv/2026-08-22-0610-avoidable-traffic-audit.md): every guide bump DMs the full v4.x body to every registrant at /register. Pull path exists (GET /guide, rule 0). Replace body push with a one-line 'guide bumped vX -> GET /guide' + changelog line. Keep LLMMSG_GUIDE_PUSH_DISABLED semantics.