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/EventParticipant.php

@@ -0,0 +1,56 @@
+<?php
+
+namespace App\Models;
+
+use App\Enums\ParticipantStatus;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+class EventParticipant extends Model
+{
+    protected $fillable = [
+        'event_id',
+        'player_id',
+        'user_id',
+        'status',
+        'note',
+        'responded_at',
+    ];
+
+    protected function casts(): array
+    {
+        return [
+            'status' => ParticipantStatus::class,
+            'responded_at' => 'datetime',
+        ];
+    }
+
+    public function event(): BelongsTo
+    {
+        return $this->belongsTo(Event::class);
+    }
+
+    public function player(): BelongsTo
+    {
+        return $this->belongsTo(Player::class)->withTrashed();
+    }
+
+    public function user(): BelongsTo
+    {
+        return $this->belongsTo(User::class)->withTrashed();
+    }
+
+    public function setByUser(): BelongsTo
+    {
+        return $this->belongsTo(User::class, 'set_by_user_id')->withTrashed();
+    }
+
+    public function participantName(): string
+    {
+        if ($this->user_id) {
+            return $this->user?->name ?? __('ui.unknown');
+        }
+
+        return $this->player?->full_name ?? __('ui.unknown');
+    }
+}