refactored to make use of the ServiceType enum throughout backend and frontend for typesafety

frontend/src/api/connections.ts

@@ -1,5 +1,5 @@
 import { apiFetch } from './client'
-import type { AuthResponse, ConnectionStatus, LoginRequest } from '../types/connection'
+import type { AuthResponse, ConnectionStatus, LoginRequest, ServiceType } from '../types/connection'
 
 export const login = (req: LoginRequest) =>
   apiFetch<AuthResponse>('/login', { method: 'POST', body: JSON.stringify(req) })
@@ -7,5 +7,5 @@ export const login = (req: LoginRequest) =>
 export const getStatuses = () =>
   apiFetch<ConnectionStatus[]>('/connections/status')
 
-export const logout = (serviceType: string) =>
+export const logout = (serviceType: ServiceType) =>
   apiFetch<void>(`/connections/${serviceType}`, { method: 'DELETE' })