aa0163d361
Conflict in agent/error_classifier.py: both simp/agent-chat and simp/agent-runtime simplified the same file. Kept simp/agent-chat's rule-table version, which already subsumes agent-runtime's billing/rate-limit/overflow verdict helpers (as _V_* verdicts + _first_match rule tables) and its dead _THINKING_SIG_PATTERNS removal. Verified with a 60k-case differential fuzz: identical ClassifiedError output vs base and vs agent-runtime's version.