Fix double /api/ prefix in API endpoint calls

When VITE_API_URL=/api, axios baseURL is already set to /api. However, all endpoint calls included the /api/ prefix, creating double paths like /api/api/auth/login/.

Removed /api/ prefix from 81 API endpoint calls across 22 files:
- src/api/auth.ts - Fixed login, logout, me, refresh, hijack endpoints
- src/api/client.ts - Fixed token refresh endpoint
- src/api/profile.ts - Fixed all profile, email, password, MFA, sessions endpoints
- src/hooks/*.ts - Fixed all remaining API calls (users, appointments, resources, etc)
- src/pages/*.tsx - Fixed signup and email verification endpoints

This ensures API requests use the correct path: /api/auth/login/ instead of /api/api/auth/login/

🤖 Generated with Claude Code

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

frontend/src/api/config.ts

@@ -3,6 +3,8 @@
  * Centralized configuration for API endpoints and settings
  */
 
+import { getBaseDomain, isRootDomain } from '../utils/domain';
+
 // Determine API base URL based on environment
 const getApiBaseUrl = (): string => {
   // In production, this would be set via environment variable
@@ -10,8 +12,15 @@ const getApiBaseUrl = (): string => {
     return import.meta.env.VITE_API_URL;
   }
 
-  // Development: use api subdomain
-  return 'http://api.lvh.me:8000';
+  // Development: build API URL dynamically based on current domain
+  const baseDomain = getBaseDomain();
+  const protocol = window.location.protocol;
+
+  // For localhost or lvh.me, use port 8000
+  const isDev = baseDomain === 'localhost' || baseDomain === 'lvh.me';
+  const port = isDev ? ':8000' : '';
+
+  return `${protocol}//api.${baseDomain}${port}`;
 };
 
 export const API_BASE_URL = getApiBaseUrl();
@@ -24,8 +33,8 @@ export const getSubdomain = (): string | null => {
   const hostname = window.location.hostname;
   const parts = hostname.split('.');
 
-  // lvh.me without subdomain (root domain) - no business context
-  if (hostname === 'lvh.me') {
+  // Root domain (no subdomain) - no business context
+  if (isRootDomain()) {
     return null;
   }