Wire the squad native adapter instead of the core registration

Why: Backend has to keep the same squad runs after the core stopped importing agent-native. The adapter module owns the concrete client.
Evidence: GOWORK=off go test -count=1 ./internal/... passed.
Impact: AgentNativeOptions now returns the adapter config. Default roles still use the agent-system backend.
Refs: D1
Co-authored-by: Cursor <cursoragent@cursor.com>

go.mod

@@ -6,17 +6,19 @@ require (
 	agent-command v0.0.0
 	agent-intent v0.0.0
 	agent-native v0.0.0
-	agent-squad v0.0.0-00010101000000-000000000000
+	agent-squad v0.0.0
+	agent-squad/adapters/native v0.0.0
 	agent-system-core v0.0.0
+	error-code-system v0.0.0
 	github.com/jackc/pgx/v5 v5.9.2
 	github.com/ledongthuc/pdf v0.0.0-20260907135840-6c8c28e0e8a0
 	github.com/redis/go-redis/v9 v9.14.0
 	golang.org/x/crypto v0.56.0
+	logging-system v0.0.0
 	modernc.org/sqlite v1.60.1
 )
 
 require (
-	error-code-system v0.0.0 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
@@ -30,7 +32,6 @@ require (
 	golang.org/x/sync v0.23.0 // indirect
 	golang.org/x/sys v0.48.0 // indirect
 	golang.org/x/text v0.41.0 // indirect
-	logging-system v0.0.0 // indirect
 	modernc.org/libc v1.77.1 // indirect
 	modernc.org/mathutil v1.7.1 // indirect
 	modernc.org/memory v1.12.1 // indirect
@@ -40,6 +41,8 @@ replace agent-intent => ./deps/agent-intent
 
 replace agent-squad => ./deps/agent-squad
 
+replace agent-squad/adapters/native => ./deps/agent-squad/adapters/native
+
 replace agent-native => ./deps/agent-native
 
 replace agent-system-core => ./deps/agent-system-core