Stand: SMTP-Test, Admin-Mail-Tab, Notifiable-Fix, Lazy-Quill

- Fix: Notifiable-Trait zum User-Model hinzugefuegt (behebt notify()-500er)
- Installer: SMTP-Verbindungstest mit EsmtpTransport + Ueberspringen-Link
- Admin: Neuer E-Mail-Tab mit SMTP-Konfiguration + Verbindungstest
- Admin: Lazy Quill-Initialisierung (nur sichtbare Locale wird geladen)
- Uebersetzungen: 17 neue Mail-Keys in allen 6 Sprachen

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

app/Models/Invitation.php

@@ -0,0 +1,52 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\Relations\BelongsToMany;
+
+class Invitation extends Model
+{
+    public $timestamps = false;
+
+    protected $fillable = [
+        'email',
+        'expires_at',
+        'created_at',
+    ];
+
+    protected function casts(): array
+    {
+        return [
+            'expires_at' => 'datetime',
+            'accepted_at' => 'datetime',
+            'created_at' => 'datetime',
+        ];
+    }
+
+    public function creator(): BelongsTo
+    {
+        return $this->belongsTo(User::class, 'created_by')->withTrashed();
+    }
+
+    public function players(): BelongsToMany
+    {
+        return $this->belongsToMany(Player::class, 'invitation_players');
+    }
+
+    public function isValid(): bool
+    {
+        return $this->accepted_at === null && $this->expires_at->isFuture();
+    }
+
+    public function isAccepted(): bool
+    {
+        return $this->accepted_at !== null;
+    }
+
+    public function scopeValid($query)
+    {
+        return $query->whereNull('accepted_at')->where('expires_at', '>', now());
+    }
+}