fix: allow agent JWT to use attached online_db_id (Z14c)

Agent tokens use agent_id as user_id while Binding is under the human member; authorize schema/push/ensure against the agent's mounted OnlineDBID.

Co-authored-by: Cursor <cursoragent@cursor.com>

platform/internal/handler/agent_online_acl_test.go

@@ -0,0 +1,20 @@
+package handler
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"aijianzhan/platform/internal/authx"
+)
+
+func TestAgentOwnsOnlineDBUsesContextAgent(t *testing.T) {
+	// 无 Agents store 时必须安全返回 false
+	r := httptest.NewRequest(http.MethodPost, "/", nil)
+	ctx := authx.WithFullClaims(context.Background(), 2, 99, authx.Role智能体, 99, 0, []string{authx.Perm数据同步})
+	r = r.WithContext(ctx)
+	if agentOwnsOnlineDB(nil, r, 2, "ch1", "ch1_u3") {
+		t.Fatal("expected false without svc")
+	}
+}