Add AgentWatch - Multi-agent observability with cascade failure detection

**Project**: [AgentWatch](https://github.com/nicofains1/agentwatch) **npm**: @nicofains1/agentwatch **Category**: Agent/LLM Observability AgentWatch detects cascade failures across multi-agent systems. While OpenTelemetry traces individual spans, AgentWatch correlates heartbeats across agents to find cross-agent failure chains that per-agent tracing misses. Features: - Heartbeat registration with cross-agent correlation - Cascade failure detection (traces backward through agent chains) - Fleet dashboard (health of all agents at a glance) - Forensic replay (stored payloads at each hop) - Self-hosted SQLite, zero external dependencies - 16 tests passing, MIT licensed Relevant to this list because it fills the gap between OTel span tracing and fleet-level agent monitoring. Article on what OTel agent conventions miss: https://nicolasfainstein.hashnode.dev/opentelemetry-now-has-agent-span-conventions-heres-what-they-miss