feat: Add audit logging (#38189)

Co-authored-by: bircni <bircni@users.noreply.github.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

services/auth/credential.go

@@ -0,0 +1,21 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package auth
+
+import (
+	"strconv"
+
+	"gitea.dev/modules/web/middleware"
+)
+
+// Credential kinds naming how a request authenticated, recorded so an audit
+// event can point at the token rather than only at its owner.
+const (
+	credentialAccessToken = "access-token"
+	credentialOAuth2Grant = "oauth2-grant"
+)
+
+func setAuthCredential(store DataStore, kind string, id int64) {
+	store.GetData()[middleware.ContextDataKeyAuthCredential] = kind + ":" + strconv.FormatInt(id, 10)
+}