feat: Handle errors, validate model names, and calculate quota usage (#978)

- Improved error handling in various modules for better stability and responsiveness.
- Optimized code in several files for improved efficiency and readability.
- Enhanced user experience by providing more detailed error responses in the controller.
- Strengthened security by ignoring sensitive files in `.gitignore`.

common/embed-file-system.go

@@ -15,10 +15,7 @@ type embedFileSystem struct {
 
 func (e embedFileSystem) Exists(prefix string, path string) bool {
 	_, err := e.Open(path)
-	if err != nil {
-		return false
-	}
-	return true
+	return err == nil
 }
 
 func EmbedFolder(fsEmbed embed.FS, targetPath string) static.ServeFileSystem {