Add QUIC fabric transport adapter

docs/architecture/DISTRIBUTED_FABRIC_NODE_PROTOCOL_PLAN.md

@@ -294,6 +294,9 @@ reuses, opens, closed-pump evictions, and explicit close operations.
 The mesh package now exposes a service-neutral `FabricTransport` abstraction;
 the current WebSocket carrier implements it as `WebSocketFabricTransport`, so
 future QUIC/UDP transport can be added without changing VPN/RDP/HTTP services.
+`QUICFabricTransport` now implements the same interface and carries the same
+binary `fabricproto` frames over a QUIC stream, with local smoke coverage for
+`PING`/`PONG` and DATA/ACK.
 
 Deliverables:
 
@@ -323,6 +326,8 @@ Deliverables:
 
 ### Stage FNP-6: QUIC/UDP Transport
 
+Status: started with `QUICFabricTransport` in `internal/mesh`.
+
 Deliverables:
 
 - implement QUIC transport for Fabric Data Session V1;