refactor: use tailscale api for user checking instead of tsnet

internal/service/oauth_extractors.go

@@ -1,10 +1,7 @@
 package service
 
 import (
-	"encoding/json"
 	"errors"
-	"fmt"
-	"io"
 	"net/http"
 	"strconv"
 
@@ -75,38 +72,3 @@ func githubExtractor(client *http.Client, _ string) (*model.Claims, error) {
 
 	return &user, nil
 }
-
-func simpleReq[T any](client *http.Client, url string, headers map[string]string) (*T, error) {
-	var decodedRes T
-
-	req, err := http.NewRequest("GET", url, nil)
-	if err != nil {
-		return nil, err
-	}
-
-	for key, value := range headers {
-		req.Header.Add(key, value)
-	}
-
-	res, err := client.Do(req)
-	if err != nil {
-		return nil, err
-	}
-	defer res.Body.Close()
-
-	if res.StatusCode < 200 || res.StatusCode >= 300 {
-		return nil, fmt.Errorf("request failed with status: %s", res.Status)
-	}
-
-	body, err := io.ReadAll(res.Body)
-	if err != nil {
-		return nil, err
-	}
-
-	err = json.Unmarshal(body, &decodedRes)
-	if err != nil {
-		return nil, err
-	}
-
-	return &decodedRes, nil
-}