feat: Add texture rendering endpoints and service methods

- Introduced new API endpoints for rendering textures, avatars, capes, and previews, enhancing the texture handling capabilities.
- Implemented corresponding service methods in the TextureHandler to process rendering requests and return appropriate responses.
- Updated the TextureRenderService interface to include methods for rendering textures, avatars, and capes, along with their respective parameters.
- Enhanced error handling for invalid texture IDs and added support for different rendering types and formats.
- Updated go.mod to include the webp library for image processing.

internal/handler/routes.go

@@ -108,6 +108,10 @@ func registerTextureRoutes(v1 *gin.RouterGroup, h *TextureHandler, jwtService *a
 		// 公开路由（无需认证）
 		textureGroup.GET("", h.Search)
 		textureGroup.GET("/:id", h.Get)
+		textureGroup.GET("/:id/render", h.RenderTexture) // type/front/back/full/head/isometric
+		textureGroup.GET("/:id/avatar", h.RenderAvatar)  // mode=2d/3d
+		textureGroup.GET("/:id/cape", h.RenderCape)
+		textureGroup.GET("/:id/preview", h.RenderPreview) // 自动根据类型预览
 
 		// 需要认证的路由
 		textureAuth := textureGroup.Group("")