added golangci-linting, refactor, simplified error msgs and fixed some error handling

internal/api/v1/index.go

@@ -1,7 +1,11 @@
 package v1
 
-import "net/http"
+import (
+	"net/http"
+
+	. "github.com/yusing/go-proxy/internal/api/v1/utils"
+)
 
 func Index(w http.ResponseWriter, r *http.Request) {
-	w.Write([]byte("API ready"))
+	WriteBody(w, []byte("API ready"))
 }