Add erasure-coded multi-lane spread foundation.

Server Reed-Solomon 4+2 shard encode on deploy plans when erasure_lanes_enabled; agents reassemble from parallel lane URLs as staging fallback with BGP/Path Tracer hints.

agent/go.mod

@@ -6,7 +6,9 @@ require (
 	git.gammaspectra.live/P2Pool/go-randomx v1.0.0
 	github.com/google/uuid v1.6.0
 	github.com/gorilla/websocket v1.5.3
+	github.com/klauspost/reedsolomon v1.12.4
 	github.com/libp2p/go-libp2p v0.48.0
+	golang.org/x/crypto v0.48.0
 	golang.org/x/sys v0.41.0
 )
 
@@ -24,7 +26,7 @@ require (
 	github.com/ipfs/go-cid v0.5.0 // indirect
 	github.com/jackpal/go-nat-pmp v1.0.2 // indirect
 	github.com/jbenet/go-temp-err-catcher v0.1.0 // indirect
-	github.com/klauspost/cpuid/v2 v2.2.10 // indirect
+	github.com/klauspost/cpuid/v2 v2.3.0 // indirect
 	github.com/koron/go-ssdp v0.0.6 // indirect
 	github.com/libp2p/go-buffer-pool v0.1.0 // indirect
 	github.com/libp2p/go-flow-metrics v0.2.0 // indirect
@@ -83,7 +85,6 @@ require (
 	go.uber.org/mock v0.5.2 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
 	go.uber.org/zap v1.27.0 // indirect
-	golang.org/x/crypto v0.48.0 // indirect
 	golang.org/x/exp v0.0.0-20250606033433-dcc06ee1d476 // indirect
 	golang.org/x/mod v0.32.0 // indirect
 	golang.org/x/net v0.50.0 // indirect