chore(ui): textura do panel gradient quadrado + ignore /AutoCreated

- Adiciona as 3 texturas que o refactor de panel referencia via
  EUIPanelTexture::Rectangle_Square_Gradient_01 (background gradient,
  outline e outline effect) em /UI/Themes/Default/Panel/.
- Ignora Content/AutoCreated/ no .gitignore: pasta de saida do
  ZeusUMGForge web converter, regenerada sob demanda, nao deve ser
  versionada.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -29,3 +29,6 @@ desktop.ini
 *.log
 *.pdb
 .vscode/
+
+# Hyper / ZeusUMGForge web converter outputs (assets gerados, não versionar)
+Content/AutoCreated/