apollo-observability

# Apollo Observability ## Overview Comprehensive observability for Apollo.io integrations: Prometheus metrics (request count, latency, rate limits, credits), structured logging with PII redaction, OpenTelemetry tracing, and alerting rules. Tracks the metrics that matter: credit burn rate, enrichment success rate, and API health. ## Prerequisites - Valid Apollo API key - Node.js 18+ ## Instructions ### Step 1: Prometheus Metrics ```typescript // src/observability/metrics.ts import { Counter, Histogram, Gauge, Registry } from 'prom-client'; export const registry = new Registry(); export const requestsTotal = new Counter({ name: 'apollo_requests_total', help: 'Total Apollo API requests by endpoint and status', labelNames: ['endpoint', 'method', 'status'] as const, registers: [registry], }); export const requestDuration = new Histogram({ name: 'apollo_request_duration_seconds', help: 'Apollo API request duration', labelNames: ['endpoint'] as const, buckets: [0.1, 0.25, 0.5, 1, 2.5, 5, 10], registers: [registry], }); export const rateLimitRemaining = new Gauge({ name: 'apollo_rate_limit_remaining', help: 'Remaining requests in current rate limit window', labelNames: ['endpoint'] as const, registers: [registry], }); export const creditsUsed = new Counter({ name: 'apollo_credits_used_total', help: 'Total Apollo enrichment credits consumed', labelNames: ['type'] as const, // 'person', 'organization', 'bulk' registers: [registry], }); expor...