chore(frontend): Refactoring

Refactoring zodat de structuur van de authenticatieservice in de client duidelijker is.

frontend/src/views/CallbackPage.vue

@@ -0,0 +1,24 @@
+<script setup lang="ts">
+    import {useRouter} from "vue-router";
+    import {onMounted} from "vue";
+    import auth from "../services/auth/auth-service.ts"
+
+    const router = useRouter();
+
+    onMounted(async () => {
+        try {
+            await auth.handleLoginCallback();
+            await router.replace("/"); // Redirect to home (or dashboard)
+        } catch (error) {
+            console.error("OIDC callback error:", error);
+        }
+    });
+</script>
+
+<template>
+    <p>Logging you in...</p>
+</template>
+
+<style scoped>
+
+</style>