GHSA-V2JF-442R-6MJH nebula-mesh: Signed-poll nonce LRU is in-memory and bounded; replay survives restart + eviction

internal/api/pop/nonce.go:25,40,86 + internal/api/server.go:38 — the signed-poll nonce cache is an in-process LRU sized at 65,536 entries. internal/api/updates.go:31 sets pollClockSkew = 5 time.Minute as the replay window. Affected All released versions through v0.3.0 that have shipped the ADR 00...