docs: KV events + Mooncake Store integration plan

[stmatengss]

Summary

Adds an implementation plan for publishing standards-aligned KV cache events across all Mooncake Store memory tiers (GPU, host/L2, Mooncake L3), enabling cache-aware routing with Dynamo KV router and Mooncake KvIndexer (RFC #1527).

Plan location

docs/superpowers/plans/2026-06-28-kv-events-mooncake-store.md

Key points

• Current state: TokenSpeed already publishes device-tier (GPU) events via ZMQ in Dynamo-compatible msgpack format; Mooncake L3 backup/prefetch works but emits no KV events.
• Gaps: No medium tier tagging, FNV/SHA256 hash mismatch vs RFC #1527 XXH3-64, no host or L3 event streams.
• Phased approach: Hash unification → RFC envelope → host/cpu events → engine L3 events → optional Mooncake master relay → Dynamo indexer validation.

References

• Mooncake RFC #1527
• Dynamo KV events for custom engines
• Dynamo PR #8912 (multi-tier indexer)
• Mooncake PR #2214 (master KV events publisher)