chore: move some types to model

internal/model/link.go

@@ -0,0 +1,21 @@
+package model
+
+import (
+	"io"
+	"net/http"
+	"time"
+)
+
+type LinkArgs struct {
+	IP     string
+	Header http.Header
+}
+
+type Link struct {
+	URL        string
+	Header     http.Header    // needed header
+	Data       io.ReadCloser  // return file reader directly
+	Status     int            // status maybe 200 or 206, etc
+	FilePath   *string        // local file, return the filepath
+	Expiration *time.Duration // url expiration time
+}