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>

vendor/laravel/sail/stubs/devcontainer.stub

@@ -0,0 +1,27 @@
+// https://aka.ms/devcontainer.json
+{
+	"name": "Existing Docker Compose (Extend)",
+	"dockerComposeFile": [
+		"../compose.yaml"
+	],
+	"service": "laravel.test",
+	"workspaceFolder": "/var/www/html",
+	"customizations": {
+		"vscode": {
+			"extensions": [
+				// "laravel.vscode-laravel",
+				// "mikestead.dotenv",
+				// "amiralizadeh9480.laravel-extra-intellisense",
+				// "ryannaddy.laravel-artisan",
+				// "onecentlin.laravel5-snippets",
+				// "onecentlin.laravel-blade"
+			],
+			"settings": {}
+		}
+	},
+	"remoteUser": "sail",
+	"postCreateCommand": "chown -R 1000:1000 /var/www/html 2>/dev/null || true"
+	// "forwardPorts": [],
+	// "runServices": [],
+	// "shutdownAction": "none",
+}