feat(admin): 「租户 & 用户」页接真实成员管理（删掉 mock）

此前整页是硬编码 mock（假租户/假用户/假 API key/假日预算）。重写为真数据：
- 左：租户目录（listTenants：名称/slug/plan/成员数/积分余额）+ 建租户表单
  （名称/slug/可选 owner 邮箱）。
- 右：选定租户成员表（listMembers）——按邮箱加成员+选角色、行内改角色、移除；
  owner 受保护（不可改角色/移除）。api 加 listTenants/createTenant/listMembers/
  addMember/setMemberRole/removeMember。

live 验证(preview)：14 个真实租户带成员数/余额；UI 加 demoB→Dexter「2 成员」、
成员表 owner 保护 + 成员可改角色/移除、移除后回 1 成员，全过；tsc + 41 测试全过。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

sundynix-admin/src/api.ts

@@ -438,3 +438,65 @@ export async function adminUsage(params?: { tenant?: string; from?: string; to?:
   const d = (await res.json()) as UsageReport;
   return { ...d, trend: d.trend ?? [], tenants: d.tenants ?? [] }; // Go 空切片可能序列化为 null
 }
+
+// —— 多成员租户：租户目录 + 成员管理 ——
+export interface TenantRow {
+  id: string;
+  name: string;
+  slug: string;
+  plan: string;
+  status: string;
+  credit_balance_micro: number;
+  members: number;
+}
+export interface Member {
+  user_id: string;
+  email: string;
+  name: string;
+  role: string; // owner / admin / member / viewer / billing_admin
+  status: string;
+  joined_at: string;
+}
+
+export async function listTenants(): Promise<TenantRow[]> {
+  const res = guard(await fetch(`${ADMIN}/tenants`, { headers: authHeaders() }));
+  if (!res.ok) throw new Error(`list tenants failed: ${res.status}`);
+  return ((await res.json()) as { tenants?: TenantRow[] }).tenants ?? [];
+}
+
+export async function createTenant(name: string, slug: string, ownerEmail?: string): Promise<void> {
+  const res = guard(await fetch(`${ADMIN}/tenants`, { method: "POST", headers: authHeaders(true), body: JSON.stringify({ name, slug, owner_email: ownerEmail ?? "" }) }));
+  const d = (await res.json().catch(() => ({}))) as { error?: string; warn?: string };
+  if (!res.ok) throw new Error(d.error ?? `create tenant failed: ${res.status}`);
+  if (d.warn) throw new Error(d.warn); // 租户已建但指定 owner 失败 → 当提示
+}
+
+export async function listMembers(tenantId: string): Promise<Member[]> {
+  const res = guard(await fetch(`${ADMIN}/tenants/${tenantId}/members`, { headers: authHeaders() }));
+  if (!res.ok) throw new Error(`list members failed: ${res.status}`);
+  return ((await res.json()) as { members?: Member[] }).members ?? [];
+}
+
+export async function addMember(tenantId: string, email: string, role: string): Promise<void> {
+  const res = guard(await fetch(`${ADMIN}/tenants/${tenantId}/members`, { method: "POST", headers: authHeaders(true), body: JSON.stringify({ email, role }) }));
+  if (!res.ok) {
+    const d = (await res.json().catch(() => ({}))) as { error?: string };
+    throw new Error(d.error ?? `add member failed: ${res.status}`);
+  }
+}
+
+export async function setMemberRole(tenantId: string, uid: string, role: string): Promise<void> {
+  const res = guard(await fetch(`${ADMIN}/tenants/${tenantId}/members/${uid}`, { method: "PUT", headers: authHeaders(true), body: JSON.stringify({ role }) }));
+  if (!res.ok) {
+    const d = (await res.json().catch(() => ({}))) as { error?: string };
+    throw new Error(d.error ?? `set role failed: ${res.status}`);
+  }
+}
+
+export async function removeMember(tenantId: string, uid: string): Promise<void> {
+  const res = guard(await fetch(`${ADMIN}/tenants/${tenantId}/members/${uid}`, { method: "DELETE", headers: authHeaders() }));
+  if (!res.ok) {
+    const d = (await res.json().catch(() => ({}))) as { error?: string };
+    throw new Error(d.error ?? `remove member failed: ${res.status}`);
+  }
+}