Add Champion model, form validation, and components for StreamerPanel.

- Added Champion model to StreamerPanelController.
- Implemented form validation for champion_id, platform, username, and displayname in create and update methods.
- Created StreamerCreateForm and StreamersTable components for better organization.

resources/css/app.css

@@ -118,4 +118,4 @@
   font-style: normal;
   font-weight: 900;
   src: url('/fonts/inter-v13-latin-900.woff2') format('woff2'); /* Chrome 36+, Opera 23+, Firefox 39+, Safari 12+, iOS 10+ */
-}
+}