qa-observability

@vslvslv

Observability-driven failure RCA agent (BL-057). When any QA skill reports a failure, this agent runs a HolmesGPT-style root cause analysis loop: fetches the test's network requests, queries backend logs for the 30s window around the failure, retrieves OTel spans for the trace ID, and synthesizes a root cause statement. Appends a FAILURE_REASON block to the test report. Only activates when observability stack is configured (OTEL_EXPORTER_OTLP_ENDPOINT, LOKI_URL, JAEGER_URL, or TEMPO_URL). Works standalone or as a post-failure hook invoked by any qa-* skill