coverage 2

Compaction quality / hallucination detector: when a conversation span is compacted, check on two axes that key information survived 鈥?FIDELITY (assertions in the summary must be found verbatim in the original leaf events, else flagged as fabricated) and C

测试覆盖率分析：解析 LCOV / Cobertura / Istanbul-JSON / Go cover.out 覆盖率报告，产出结构化覆盖率数据与未覆盖行区间，指导补写测试