Alias the core package consistently

Why: An interrupted import cleanup removed the cmdbus core import while two human-decision files used an explicit alias.

Evidence: go test ./internal/cmdbus ./internal/server passes.

Impact: The backend worktree is buildable and consistently names the core package without behavior changes.

Refs: W4b human decision verifier

internal/cmdbus/cmdbus.go

@@ -16,7 +16,7 @@ import (
 	"time"
 
 	agentcommand "agent-command"
-	"agent-system-core"
+	core "agent-system-core"
 )
 
 // AuditStore 审计落盘端口（store 实现；v7 建表、v18 加 owner 列）。

internal/server/human_decision.go

@@ -1,6 +1,7 @@
 package server
 
 import (
+	core "agent-system-core"
 	"errors"
 	"net/http"
 	"strconv"
@@ -9,7 +10,6 @@ import (
 
 	"agent-system-backend/internal/cmdbus"
 	"agent-system-backend/internal/store"
-	"agent-system-core"
 )
 
 // resolveHumanDecision handles a card issued by HumanDecisionVerifier.

internal/server/human_decision_test.go

@@ -1,6 +1,7 @@
 package server
 
 import (
+	core "agent-system-core"
 	"context"
 	"net/http/httptest"
 	"testing"
@@ -10,7 +11,6 @@ import (
 	"agent-system-backend/internal/cmdbus"
 	"agent-system-backend/internal/store"
 	"agent-system-backend/pkg/extension"
-	"agent-system-core"
 )
 
 type nopHumanAudit struct{}