Overhaul [1/n]

Signed-off-by: Sean Du <do4suki@gmail.com>

internal/handler/api/challenge/challenge.go

@@ -0,0 +1,15 @@
+package challenge
+
+import (
+	"fmt"
+)
+
+func ChallengeApi(action string) (res any, err error) {
+	switch action {
+	case "challengeInfo":
+		res, err = challengeInfo()
+	default:
+		err = fmt.Errorf("unimplemented action: challenge: %s", action)
+	}
+	return res, err
+}