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/hooks/useCustomers.ts

@@ -22,7 +22,7 @@ export const useCustomers = (filters?: CustomerFilters) => {
       if (filters?.status) params.append('status', filters.status);
       if (filters?.search) params.append('search', filters.search);
 
-      const { data } = await apiClient.get(`/api/customers/?${params}`);
+      const { data } = await apiClient.get(`/customers/?${params}`);
 
       // Transform backend format to frontend format
       return data.map((c: any) => ({
@@ -66,7 +66,7 @@ export const useCreateCustomer = () => {
         tags: customerData.tags,
       };
 
-      const { data } = await apiClient.post('/api/customers/', backendData);
+      const { data } = await apiClient.post('/customers/', backendData);
       return data;
     },
     onSuccess: () => {
@@ -93,7 +93,7 @@ export const useUpdateCustomer = () => {
         tags: updates.tags,
       };
 
-      const { data } = await apiClient.patch(`/api/customers/${id}/`, backendData);
+      const { data } = await apiClient.patch(`/customers/${id}/`, backendData);
       return data;
     },
     onSuccess: () => {
@@ -110,7 +110,7 @@ export const useDeleteCustomer = () => {
 
   return useMutation({
     mutationFn: async (id: string) => {
-      await apiClient.delete(`/api/customers/${id}/`);
+      await apiClient.delete(`/customers/${id}/`);
     },
     onSuccess: () => {
       queryClient.invalidateQueries({ queryKey: ['customers'] });