Add vue-router, login/setup flow and backend logging

Refactor frontend to route-based navigation with vue-router, add
system setup and login pages with API integration. Add structured
logging, access-log middleware and startup lifecycle to FastAPI
backend.

web/src/main.js

@@ -4,10 +4,12 @@ import PrimeVue from 'primevue/config'
 import Aura from '@primevue/themes/aura'
 import 'primeicons/primeicons.css'
 import App from './App.vue'
+import router from './router/index.js'
 
 const app = createApp(App)
 
 app.use(MotionPlugin)
+app.use(router)
 app.use(PrimeVue, {
   theme: {
     preset: Aura,