Move the Messaging API back out of pkg/kernel: ffi.Handle becomes a
defined type in the internal package, so kernel can hand the context to
pkg/messaging through kernel.Handle without the kernel layer knowing the
tier exists, and without the type being nameable outside this module.
Split Discovery into DiscV5, PeerExchange and DNSDiscovery, group the
node's identity and health under Debug(), and give every facade a pointer
receiver. Drop the node name, the per-operation logging that duplicates
what the library already writes, and GetFreePortIfNeeded — port 0 already
means "let the OS pick".
Heavy kernel tests now mark themselves with requiresNode and skip under
-short, so the gate runs `go test -short ./...` instead of naming tests
in a regexp.
The Kernel API and the Messaging API each built their own node and kept
the FFI handle private, so a MessagingClient had no way to reach store
queries, peers or metrics. The C library has one context serving both
tiers, so this was only a Go ownership problem.
kernel.Node now owns that context, and the kernel protocols hang off it
as facades: Relay(), Store(), Peers(), Discovery(), plus Messaging() for
the stable tier. MessagingClient drives a Node and hands it over with
Node(), mirroring the Nim MessagingClient's public waku field.
Igor Sirotin