feat(PROJ-22): LDAP Web-GUI + feat(PROJ-21): Multi-Tenancy Phase 1

PROJ-22 – LDAP Web-GUI Konfiguration & Test:
- internal/ldapconfig/store.go: AES-256-GCM Passwortspeicherung, CRUD Upsert (id=1)
- internal/ldapauth/client.go: TestConnection (RootDSE, UserCount) + Authenticate (2-step bind)
- internal/auth/auth.go: LDAP-Fallback in Login(), Gruppen-Rollenzuordnung, issueToken helper
- internal/api/ldap_tenants.go: GET/PUT/DELETE/POST-test /api/admin/ldap mit Audit-Log
- go.mod: github.com/go-ldap/ldap/v3 v3.4.8 hinzugefügt
- Frontend: LDAPConfig/LDAPTestResult Typen, LDAP-Tab mit Gruppen-Mappings + Testergebnis

PROJ-21 Phase 1+6+7 – Multi-Tenancy Grundstruktur:
- internal/tenantstore/store.go: tenants, tenant_domains, tenant_ldap Schema; Migration users/audit_log
- API: 8 Tenant-Routen (CRUD + Domain-Management) via SetTenants()
- cmd/archivmail/main.go: ldapSt + tenantSt initialisiert
- Frontend: Mandanten-Tab mit Tabelle, Domain-Dialog, Deaktivieren/Löschen

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/api.ts

@@ -599,3 +599,132 @@ export async function fixSecurityIssue(action: string): Promise<{ message: strin
     body: JSON.stringify({ action }),
   });
 }
+
+// ── LDAP ──────────────────────────────────────────────────────────────────
+
+export interface LDAPGroupMapping {
+  group_dn: string;
+  role: string;
+}
+
+export interface LDAPConfig {
+  id?: number;
+  enabled: boolean;
+  url: string;
+  bind_dn: string;
+  bind_password: string;
+  base_dn: string;
+  user_filter: string;
+  tls: boolean;
+  tls_skip_verify: boolean;
+  default_role: string;
+  group_mappings: LDAPGroupMapping[];
+  updated_at?: string;
+  updated_by?: string;
+}
+
+export interface LDAPTestResult {
+  ok: boolean;
+  message: string;
+  latency_ms: number;
+  server_info: string;
+  users_found: number;
+  error_detail: string;
+}
+
+export async function getLDAPConfig(): Promise<LDAPConfig | null> {
+  try {
+    return await request<LDAPConfig>("/api/admin/ldap");
+  } catch (e: unknown) {
+    if (e instanceof Error && e.message.includes("404")) return null;
+    if (e instanceof Error && e.message.includes("no ldap config")) return null;
+    throw e;
+  }
+}
+
+export async function saveLDAPConfig(cfg: Partial<LDAPConfig>): Promise<void> {
+  await request<void>("/api/admin/ldap", {
+    method: "PUT",
+    body: JSON.stringify(cfg),
+  });
+}
+
+export async function deleteLDAPConfig(): Promise<void> {
+  await request<void>("/api/admin/ldap", { method: "DELETE" });
+}
+
+export async function testLDAPConfig(
+  payload: { use_saved: boolean } & Partial<LDAPConfig>
+): Promise<LDAPTestResult> {
+  return request<LDAPTestResult>("/api/admin/ldap/test", {
+    method: "POST",
+    body: JSON.stringify(payload),
+  });
+}
+
+// ── Tenants ────────────────────────────────────────────────────────────────
+
+export interface Tenant {
+  id: number;
+  name: string;
+  slug: string;
+  active: boolean;
+  created_at: string;
+  domain_count?: number;
+  user_count?: number;
+}
+
+export interface TenantDomain {
+  id: number;
+  tenant_id: number;
+  domain: string;
+  created_at: string;
+}
+
+export async function getTenants(): Promise<Tenant[]> {
+  return request<Tenant[]>("/api/tenants");
+}
+
+export async function createTenant(name: string, slug: string): Promise<Tenant> {
+  return request<Tenant>("/api/tenants", {
+    method: "POST",
+    body: JSON.stringify({ name, slug }),
+  });
+}
+
+export async function updateTenant(
+  id: number,
+  data: { name?: string; active?: boolean }
+): Promise<Tenant> {
+  return request<Tenant>(`/api/tenants/${id}`, {
+    method: "PATCH",
+    body: JSON.stringify(data),
+  });
+}
+
+export async function deleteTenant(id: number): Promise<void> {
+  await request<void>(`/api/tenants/${id}`, { method: "DELETE" });
+}
+
+export async function getTenantDomains(id: number): Promise<TenantDomain[]> {
+  return request<TenantDomain[]>(`/api/tenants/${id}/domains`);
+}
+
+export async function addTenantDomain(
+  tenantId: number,
+  domain: string
+): Promise<TenantDomain> {
+  return request<TenantDomain>(`/api/tenants/${tenantId}/domains`, {
+    method: "POST",
+    body: JSON.stringify({ domain }),
+  });
+}
+
+export async function removeTenantDomain(
+  tenantId: number,
+  domainId: number
+): Promise<void> {
+  await request<void>(`/api/tenants/${tenantId}/domains/${domainId}`, {
+    method: "DELETE",
+  });
+}