T4 recovery: Jev classifier, ask-once precedents, budget guardrails

classify_failure asks Jev first, then Claude, then regex. Below 0.7 confidence FirstRun asks the human once and stores the answer. Budget checks are GUARDRAIL spans. Live: Jev read chromadb==0.3 as docs_bug at 0.99 and recover() found the fix from PyPI for 0.013 USD list price.