BOLT-917 Phase 2: Activate RawApiSession + decide on backpressure for recordApiCall

Phase 1 ships the RawApiSession table empty (Smartcar commands do not currently chain calls; Phase 2 polling/webhook flows will populate it). Phase 2: (1) wire session creation around multi-call flows (token refresh + data fetch + status check), (2) revisit fire-and-forget — onApiCall is `(exchange) => void`, callers do `void recordApiCall(...)`; under spike load this silently drops rows on DB error (logged only). Consider buffered batch writer with bounded queue + drop policy, or move writes off the request path via BullMQ.