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/ActivityLog.php

@@ -0,0 +1,69 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+class ActivityLog extends Model
+{
+    public $timestamps = false;
+
+    protected $fillable = [
+        'user_id',
+        'action',
+        'model_type',
+        'model_id',
+        'description',
+        'properties',
+        'created_at',
+    ];
+
+    protected function casts(): array
+    {
+        return [
+            'properties' => 'array',
+            'created_at' => 'datetime',
+        ];
+    }
+
+    public function user(): BelongsTo
+    {
+        return $this->belongsTo(User::class)->withTrashed();
+    }
+
+    public static function log(
+        string $action,
+        string $description,
+        ?string $modelType = null,
+        ?int $modelId = null,
+        ?array $properties = null,
+    ): self {
+        $log = new static();
+        $log->user_id = auth()->id();
+        $log->action = $action;
+        $log->model_type = $modelType;
+        $log->model_id = $modelId;
+        $log->description = $description;
+        $log->properties = $properties;
+        $log->ip_address = request()->ip();
+        $log->created_at = now();
+        $log->save();
+        return $log;
+    }
+
+    public static function logWithChanges(
+        string $action,
+        string $description,
+        ?string $modelType = null,
+        ?int $modelId = null,
+        ?array $old = null,
+        ?array $new = null,
+    ): self {
+        $properties = null;
+        if ($old !== null || $new !== null) {
+            $properties = array_filter(['old' => $old, 'new' => $new], fn ($v) => $v !== null);
+        }
+        return static::log($action, $description, $modelType, $modelId, $properties ?: null);
+    }
+}