refactor: remove SendsWebhook interface

Simplified webhook channel implementation to match TelegramChannel pattern without typed interface.

Changes:
- Removed SendsWebhook interface file
- Removed interface from Team model
- Removed routeNotificationForWebhook() method
- WebhookChannel now uses untyped $notifiable like TelegramChannel

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/Notifications/Channels/SendsWebhook.php

@@ -1,8 +0,0 @@
-<?php
-
-namespace App\Notifications\Channels;
-
-interface SendsWebhook
-{
-    public function routeNotificationForWebhook();
-}

app/Notifications/Channels/WebhookChannel.php

@@ -10,7 +10,7 @@ class WebhookChannel
     /**
      * Send the given notification.
      */
-    public function send(SendsWebhook $notifiable, Notification $notification): void
+    public function send($notifiable, Notification $notification): void
     {
         $webhookSettings = $notifiable->webhookNotificationSettings;