feat: account settings with Vuexy tab pattern and MFA banner fix

Restructures account/profile pages to match Vuexy's account-settings
tab pattern (Account, Security, Notifications) and fixes the MFA
enforcement banner that stayed visible after successful setup.

Backend:
- Add phone column to users table with migration
- Add PUT /me/profile endpoint for profile updates
- Create UpdateProfileRequest form request
- Update MeResource to include phone field

Organizer app:
- Rewrite account-settings as tabbed page (VTabs pill style + VWindow)
- Create AccountTab: avatar, profile form, email change, danger zone
- Create SecurityTab: password change, MFA method cards, backup codes,
  trusted devices, disable MFA danger zone
- Create NotificationsTab: placeholder with disabled toggles
- Fix MFA banner: set authStore.mfaSetupRequired = false on setup complete
- Update router guard to redirect to ?tab=security for MFA enforcement
- Update UserProfile menu links to use tab query params

Portal:
- Restructure profiel.vue with VTabs (Mijn profiel + Beveiliging)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

api/database/migrations/2026_04_16_000000_add_phone_to_users_table.php

@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::table('users', function (Blueprint $table) {
+            $table->string('phone', 20)->nullable()->after('email');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('users', function (Blueprint $table) {
+            $table->dropColumn('phone');
+        });
+    }
+};