feat: tenants admin surface

Adds the first admin screen — /tenants — listing tenants from
GET /api/v1/admin/tenants with search, status badges, plan, created
date, and a per-row menu with suspend / activate / deactivate actions.

Hand-typed shapes in app/lib/arcadia/tenants.ts because arcadia's admin
endpoints aren't yet covered by /api/openapi (same 'ok'-placeholder
issue documented in lib-arcadia-client/scripts/sync-spec.mjs). When
the spec gains coverage, switch to arcadia.typed.GET(...) and drop the
manual types.

Trims the inherited consumer-app sidenav (Resources / Assistant / AI /
Library) down to admin-shaped items: Overview, Tenants, Audit log,
Settings. The unused route files stay in place; they just aren't linked.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/lib/arcadia/tenants.ts

@@ -0,0 +1,93 @@
+// Arcadia tenants API helpers.
+//
+// Hand-rolled because /api/v1/admin/tenants isn't covered by arcadia's
+// OpenAPI spec (controller hasn't been wired into OpenApiSpex yet — same
+// "ok"-placeholder issue as some other admin endpoints). When the spec
+// gains coverage, switch to `arcadia.typed.GET("/api/v1/admin/tenants", ...)`
+// and drop these manual types.
+
+import type { ArcadiaClient } from "@crema/arcadia-client"
+
+export type TenantStatus = "active" | "suspended" | "deactivated" | string
+
+export interface TenantPlan {
+  name: string
+  limits: Record<string, unknown>
+}
+
+export interface TenantBranding {
+  logo_url: string | null
+  favicon_url: string | null
+  primary_color: string | null
+  secondary_color: string | null
+  accent_color: string | null
+  custom_css: string | null
+  settings: Record<string, unknown>
+}
+
+export interface TenantSettings {
+  timezone?: string
+  currency?: string
+  [key: string]: unknown
+}
+
+export interface TenantLocalization {
+  locale: string
+  timezone: string
+  currency: string
+  settings: Record<string, unknown>
+}
+
+export interface Tenant {
+  id: string
+  slug: string
+  name: string
+  status: TenantStatus
+  plan: TenantPlan
+  branding: TenantBranding
+  settings: TenantSettings
+  localization: TenantLocalization
+  email_settings: Record<string, unknown>
+  notification_settings: Record<string, unknown>
+  metadata: Record<string, unknown>
+  inserted_at: string
+  updated_at: string
+}
+
+export interface TenantListParams {
+  q?: string
+  status?: TenantStatus
+  page?: number
+  per_page?: number
+}
+
+export async function listTenants(
+  arcadia: ArcadiaClient,
+  params?: TenantListParams,
+): Promise<Tenant[]> {
+  const queryParams: Record<string, string | number | boolean | null | undefined> | undefined = params
+    ? { q: params.q, status: params.status, page: params.page, per_page: params.per_page }
+    : undefined
+  const res = await arcadia.GET<{ data: Tenant[] }>("/api/v1/admin/tenants", { params: queryParams })
+  return res.data
+}
+
+export async function getTenant(arcadia: ArcadiaClient, id: string): Promise<Tenant> {
+  const res = await arcadia.GET<{ data: Tenant }>(`/api/v1/admin/tenants/${id}`)
+  return res.data
+}
+
+export async function suspendTenant(arcadia: ArcadiaClient, id: string): Promise<Tenant> {
+  const res = await arcadia.POST<{ data: Tenant }>(`/api/v1/admin/tenants/${id}/suspend`)
+  return res.data
+}
+
+export async function activateTenant(arcadia: ArcadiaClient, id: string): Promise<Tenant> {
+  const res = await arcadia.POST<{ data: Tenant }>(`/api/v1/admin/tenants/${id}/activate`)
+  return res.data
+}
+
+export async function deactivateTenant(arcadia: ArcadiaClient, id: string): Promise<Tenant> {
+  const res = await arcadia.POST<{ data: Tenant }>(`/api/v1/admin/tenants/${id}/deactivate`)
+  return res.data
+}