fix: handle os.Getwd() error silently ignored in AddStaticFiles

[SatishKumar620]

Bug Description

In AddStaticFiles function in pkg/gofr/gofr.go (line 402), the error
returned by os.Getwd() is silently ignored using _.

Current Code

currentWorkingDir, _ := os.Getwd()
filePath = filepath.Join(currentWorkingDir, filePath)
Problem
If os.Getwd() fails, currentWorkingDir becomes an empty string,
causing filePath to be resolved incorrectly without any error or log
message to the developer. This makes debugging very difficult.


##Expected Behavior
The error should be handled and logged so developers are informed when
working directory resolution fails.

[SatishKumar620]

I'd like to work on this issue. Can you please assign it to me?