feat: integra autenticação do front com API real

- useAuth.ts: substitui mock por $fetch no /auth/login e /auth/logout
- login.vue: adiciona campo "Organização" (slug) no formulário
- nuxt.config.ts: adiciona runtimeConfig.public.apiBase

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

front-end/app/pages/login.vue

@@ -5,13 +5,14 @@ definePageMeta({ layout: 'auth' })
 const { login } = useAuth()
 const email = ref('')
 const password = ref('')
+const slug = ref('')
 const error = ref('')
 const loading = ref(false)
 
 async function handleSubmit() {
   error.value = ''
   loading.value = true
-  const result = await login(email.value, password.value)
+  const result = await login(email.value, password.value, slug.value)
   loading.value = false
   if (result.success) {
     navigateTo('/')
@@ -49,6 +50,16 @@ async function handleSubmit() {
         />
       </UFormField>
 
+      <UFormField label="Organização" class="field">
+        <UInput
+          v-model="slug"
+          type="text"
+          placeholder="minha-empresa"
+          size="md"
+          required
+        />
+      </UFormField>
+
       <div class="forgot">
         <a href="#">Esqueceu a senha?</a>
       </div>