feat(frontend): add user attributes management UI

Add Vue components and API client for managing user custom attributes.

- Add userAttributes API client with CRUD operations
- Add UserAttributeForm component for displaying/editing attribute values
- Add UserAttributesConfigModal for attribute definition management
- Support all attribute types: text, textarea, number, email, url,
  date, select, multi_select

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/api/admin/index.ts

@@ -15,6 +15,7 @@ import subscriptionsAPI from './subscriptions'
 import usageAPI from './usage'
 import geminiAPI from './gemini'
 import antigravityAPI from './antigravity'
+import userAttributesAPI from './userAttributes'
 
 /**
  * Unified admin API object for convenient access
@@ -31,7 +32,8 @@ export const adminAPI = {
   subscriptions: subscriptionsAPI,
   usage: usageAPI,
   gemini: geminiAPI,
-  antigravity: antigravityAPI
+  antigravity: antigravityAPI,
+  userAttributes: userAttributesAPI
 }
 
 export {
@@ -46,7 +48,8 @@ export {
   subscriptionsAPI,
   usageAPI,
   geminiAPI,
-  antigravityAPI
+  antigravityAPI,
+  userAttributesAPI
 }
 
 export default adminAPI

frontend/src/api/admin/userAttributes.ts

@@ -0,0 +1,131 @@
+/**
+ * Admin User Attributes API endpoints
+ * Handles user custom attribute definitions and values
+ */
+
+import { apiClient } from '../client'
+import type {
+  UserAttributeDefinition,
+  UserAttributeValue,
+  CreateUserAttributeRequest,
+  UpdateUserAttributeRequest,
+  UserAttributeValuesMap
+} from '@/types'
+
+/**
+ * Get all attribute definitions
+ */
+export async function listDefinitions(): Promise<UserAttributeDefinition[]> {
+  const { data } = await apiClient.get<UserAttributeDefinition[]>('/admin/user-attributes')
+  return data
+}
+
+/**
+ * Get enabled attribute definitions only
+ */
+export async function listEnabledDefinitions(): Promise<UserAttributeDefinition[]> {
+  const { data } = await apiClient.get<UserAttributeDefinition[]>('/admin/user-attributes', {
+    params: { enabled: true }
+  })
+  return data
+}
+
+/**
+ * Create a new attribute definition
+ */
+export async function createDefinition(
+  request: CreateUserAttributeRequest
+): Promise<UserAttributeDefinition> {
+  const { data } = await apiClient.post<UserAttributeDefinition>('/admin/user-attributes', request)
+  return data
+}
+
+/**
+ * Update an attribute definition
+ */
+export async function updateDefinition(
+  id: number,
+  request: UpdateUserAttributeRequest
+): Promise<UserAttributeDefinition> {
+  const { data } = await apiClient.put<UserAttributeDefinition>(
+    `/admin/user-attributes/${id}`,
+    request
+  )
+  return data
+}
+
+/**
+ * Delete an attribute definition
+ */
+export async function deleteDefinition(id: number): Promise<{ message: string }> {
+  const { data } = await apiClient.delete<{ message: string }>(`/admin/user-attributes/${id}`)
+  return data
+}
+
+/**
+ * Reorder attribute definitions
+ */
+export async function reorderDefinitions(ids: number[]): Promise<{ message: string }> {
+  const { data } = await apiClient.put<{ message: string }>('/admin/user-attributes/reorder', {
+    ids
+  })
+  return data
+}
+
+/**
+ * Get user's attribute values
+ */
+export async function getUserAttributeValues(userId: number): Promise<UserAttributeValue[]> {
+  const { data } = await apiClient.get<UserAttributeValue[]>(
+    `/admin/users/${userId}/attributes`
+  )
+  return data
+}
+
+/**
+ * Update user's attribute values (batch)
+ */
+export async function updateUserAttributeValues(
+  userId: number,
+  values: UserAttributeValuesMap
+): Promise<{ message: string }> {
+  const { data } = await apiClient.put<{ message: string }>(
+    `/admin/users/${userId}/attributes`,
+    { values }
+  )
+  return data
+}
+
+/**
+ * Batch response type
+ */
+export interface BatchUserAttributesResponse {
+  attributes: Record<number, Record<number, string>>
+}
+
+/**
+ * Get attribute values for multiple users
+ */
+export async function getBatchUserAttributes(
+  userIds: number[]
+): Promise<BatchUserAttributesResponse> {
+  const { data } = await apiClient.post<BatchUserAttributesResponse>(
+    '/admin/user-attributes/batch',
+    { user_ids: userIds }
+  )
+  return data
+}
+
+export const userAttributesAPI = {
+  listDefinitions,
+  listEnabledDefinitions,
+  createDefinition,
+  updateDefinition,
+  deleteDefinition,
+  reorderDefinitions,
+  getUserAttributeValues,
+  updateUserAttributeValues,
+  getBatchUserAttributes
+}
+
+export default userAttributesAPI