Add admin trend stats and sign-up sparkline

Task #13: Show admin trends like new sign-ups this week.

Backend
- Added GET /api/stats/admin (admin-only) in artifacts/api-server/src/routes/stats.ts.
- Returns: newUsersLast7Days, newUsersPrev7Days, activeServices,
  inactiveServices, signupsByDay (7-day series with zero-filled days,
  computed via date_trunc on usersTable.createdAt).

API spec / codegen
- Added /stats/admin path and AdminStats schema in lib/api-spec/openapi.yaml.
- Re-ran @workspace/api-spec codegen, regenerating react-query hooks
  (useGetAdminStats) and zod schemas.

Frontend (artifacts/teaboy-os/src/pages/admin.tsx)
- Wired useGetAdminStats in AdminPage (enabled only for admins).
- Extended DashboardSection with two trend cards (new users 7d w/
  delta vs previous 7d, active services with inactive count) and a
  small bar chart of sign-ups over the last 7 days.
- Added matching i18n keys (en/ar) under admin.dashboard.

Notes
- Avoided sending all users to the client for trend computation, as
  recommended in the task brief.
- Verified pnpm typecheck passes and the new endpoint returns 401 to
  unauthenticated callers.

Replit-Task-Id: dd11d7f7-5569-47b4-878e-ad63043eda31

lib/api-client-react/src/generated/api.schemas.ts

@@ -305,3 +305,16 @@ export interface HomeStats {
   unreadMessages: number;
   totalUsers: number;
 }
+
+export type AdminStatsSignupsByDayItem = {
+  date: string;
+  count: number;
+};
+
+export interface AdminStats {
+  newUsersLast7Days: number;
+  newUsersPrev7Days: number;
+  activeServices: number;
+  inactiveServices: number;
+  signupsByDay: AdminStatsSignupsByDayItem[];
+}

lib/api-client-react/src/generated/api.ts

@@ -17,6 +17,7 @@ import type {
 } from "@tanstack/react-query";
 
 import type {
+  AdminStats,
   App,
   AppSettings,
   AuthUser,
@@ -2977,3 +2978,78 @@ export function useGetHomeStats<
 
   return { ...query, queryKey: queryOptions.queryKey };
 }
+
+/**
+ * @summary Get admin dashboard trend stats
+ */
+export const getGetAdminStatsUrl = () => {
+  return `/api/stats/admin`;
+};
+
+export const getAdminStats = async (
+  options?: RequestInit,
+): Promise<AdminStats> => {
+  return customFetch<AdminStats>(getGetAdminStatsUrl(), {
+    ...options,
+    method: "GET",
+  });
+};
+
+export const getGetAdminStatsQueryKey = () => {
+  return [`/api/stats/admin`] as const;
+};
+
+export const getGetAdminStatsQueryOptions = <
+  TData = Awaited<ReturnType<typeof getAdminStats>>,
+  TError = ErrorType<unknown>,
+>(options?: {
+  query?: UseQueryOptions<
+    Awaited<ReturnType<typeof getAdminStats>>,
+    TError,
+    TData
+  >;
+  request?: SecondParameter<typeof customFetch>;
+}) => {
+  const { query: queryOptions, request: requestOptions } = options ?? {};
+
+  const queryKey = queryOptions?.queryKey ?? getGetAdminStatsQueryKey();
+
+  const queryFn: QueryFunction<Awaited<ReturnType<typeof getAdminStats>>> = ({
+    signal,
+  }) => getAdminStats({ signal, ...requestOptions });
+
+  return { queryKey, queryFn, ...queryOptions } as UseQueryOptions<
+    Awaited<ReturnType<typeof getAdminStats>>,
+    TError,
+    TData
+  > & { queryKey: QueryKey };
+};
+
+export type GetAdminStatsQueryResult = NonNullable<
+  Awaited<ReturnType<typeof getAdminStats>>
+>;
+export type GetAdminStatsQueryError = ErrorType<unknown>;
+
+/**
+ * @summary Get admin dashboard trend stats
+ */
+
+export function useGetAdminStats<
+  TData = Awaited<ReturnType<typeof getAdminStats>>,
+  TError = ErrorType<unknown>,
+>(options?: {
+  query?: UseQueryOptions<
+    Awaited<ReturnType<typeof getAdminStats>>,
+    TError,
+    TData
+  >;
+  request?: SecondParameter<typeof customFetch>;
+}): UseQueryResult<TData, TError> & { queryKey: QueryKey } {
+  const queryOptions = getGetAdminStatsQueryOptions(options);
+
+  const query = useQuery(queryOptions) as UseQueryResult<TData, TError> & {
+    queryKey: QueryKey;
+  };
+
+  return { ...query, queryKey: queryOptions.queryKey };
+}

lib/api-spec/openapi.yaml

@@ -704,6 +704,19 @@ paths:
               schema:
                 $ref: "#/components/schemas/HomeStats"
 
+  /stats/admin:
+    get:
+      operationId: getAdminStats
+      tags: [stats]
+      summary: Get admin dashboard trend stats
+      responses:
+        "200":
+          description: Admin stats
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/AdminStats"
+
 components:
   schemas:
     HealthStatus:
@@ -1287,3 +1300,33 @@ components:
         - unreadNotifications
         - unreadMessages
         - totalUsers
+
+    AdminStats:
+      type: object
+      properties:
+        newUsersLast7Days:
+          type: integer
+        newUsersPrev7Days:
+          type: integer
+        activeServices:
+          type: integer
+        inactiveServices:
+          type: integer
+        signupsByDay:
+          type: array
+          items:
+            type: object
+            properties:
+              date:
+                type: string
+              count:
+                type: integer
+            required:
+              - date
+              - count
+      required:
+        - newUsersLast7Days
+        - newUsersPrev7Days
+        - activeServices
+        - inactiveServices
+        - signupsByDay

lib/api-zod/src/generated/api.ts

@@ -688,3 +688,19 @@ export const GetHomeStatsResponse = zod.object({
   unreadMessages: zod.number(),
   totalUsers: zod.number(),
 });
+
+/**
+ * @summary Get admin dashboard trend stats
+ */
+export const GetAdminStatsResponse = zod.object({
+  newUsersLast7Days: zod.number(),
+  newUsersPrev7Days: zod.number(),
+  activeServices: zod.number(),
+  inactiveServices: zod.number(),
+  signupsByDay: zod.array(
+    zod.object({
+      date: zod.string(),
+      count: zod.number(),
+    }),
+  ),
+});