feat(users): fetch user by id from backend

lib/api/users.ts

@@ -1,4 +1,5 @@
 import { httpJson } from "@/lib/api/http"
+import { isApiError } from "@/lib/errors"
 import { mockUsers } from "@/lib/mock"
 import type { User } from "@/lib/types"
 
@@ -6,8 +7,13 @@ export function listUsers() {
   return mockUsers
 }
 
-export function getUserById(userId: string) {
-  return mockUsers.find((user) => user.id === userId)
+export async function getUserById(userId: string): Promise<User | undefined> {
+  try {
+    return await httpJson<User>(`/api/v1/users/${userId}`)
+  } catch (err) {
+    if (isApiError(err) && err.code === 404) return undefined
+    throw err
+  }
 }
 
 export async function getCurrentUserForLogin(): Promise<User> {