feat: 接入 Database 三资源 API 与分层绑定协调

确定单库单账号、集群级 Database、资源侧先写绑定和凭据定位合同。领域层承载纯规则，service 协調流程，Kubernetes adapter 负责资源呈现与版本保护。

验证：全量 make test、三轮 race、真实 API server 并发与重启补写、最小 RBAC/watch、lint 和文档检查通过。供应、凭据交付及删除清理尚未实现，保留 DeletionPending/finalizer 边界。

api/database/v1alpha1/groupversion_info.go

@@ -0,0 +1,25 @@
+// Package v1alpha1 定义 Database 领域的 Kubernetes API。
+// +kubebuilder:object:generate=true
+// +groupName=database.ayatori.ddupan.top
+package v1alpha1
+
+import (
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+)
+
+var (
+	SchemeGroupVersion = schema.GroupVersion{Group: "database.ayatori.ddupan.top", Version: "v1alpha1"}
+	GroupVersion       = SchemeGroupVersion
+	SchemeBuilder      = runtime.NewSchemeBuilder(func(scheme *runtime.Scheme) error {
+		scheme.AddKnownTypes(SchemeGroupVersion,
+			&PostgreSQLInstance{}, &PostgreSQLInstanceList{},
+			&PostgreSQLDatabase{}, &PostgreSQLDatabaseList{},
+			&PostgreSQLTenant{}, &PostgreSQLTenantList{},
+		)
+		metav1.AddToGroupVersion(scheme, SchemeGroupVersion)
+		return nil
+	})
+	AddToScheme = SchemeBuilder.AddToScheme
+)