v5.27.0

CLAUDE.md now requires that sub-agents never spawn on haiku or small models because they thrash context, and always use the opus or primary model (i.e. GLM-5.3) for sub-agents and agent teams. This closes the gap where CLAUDE_CODE_SUBAGENT_MODEL only pins the default and an explicit haiku-class spawn still landed on glm-5.3-flash[1m]. The stale GLM-5.1 example is corrected.