feat(profile): add username + preferred_locale; wire to Inertia + middleware

- DB: users.username (unique), users.preferred_locale (default from app.locale)
- Backend: validation, model fillable; share supportedLocales; SetLocaleFromUser
- Frontend: profile page fields + types
- Filament: SuperAdmin profile page with username/language

feat(admin-nav): move Tasks to Bibliothek and add menu labels

fix(tasks-table): show localized title/emotion/event type; add translated headers

feat(l10n): add missing table headers for emotions and event types; normalize en/de files

refactor: tidy translations for tasks/emotions/event types

app/Http/Middleware/SetLocaleFromUser.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace App\Http\Middleware;
+
+use Closure;
+use Illuminate\Http\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+class SetLocaleFromUser
+{
+    public function handle(Request $request, Closure $next): Response
+    {
+        $user = $request->user();
+
+        if ($user && ! empty($user->preferred_locale)) {
+            app()->setLocale($user->preferred_locale);
+        }
+
+        return $next($request);
+    }
+}
+