Replace custom Go formatter with golangci-lint fmt (#37194)

Use `golangci-lint fmt` to format code, replacing the previous custom
formatter tool. https://github.com/daixiang0/gci is used to order the
imports.

`make fmt` performs ~13% faster while consuming ~57% less cpu while
formatting for me.

`GOFUMPT_PACKAGE` is gone because it's using the builtin package from
golangci-lint.

Co-authored-by: Claude (claude-opus-4-6) <noreply@anthropic.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/avatar/avatar.go

@@ -11,15 +11,14 @@ import (
 	"image/color"
 	"image/png"
 
-	_ "image/gif"  // for processing gif images
-	_ "image/jpeg" // for processing jpeg images
-
 	"code.gitea.io/gitea/modules/avatar/identicon"
 	"code.gitea.io/gitea/modules/setting"
 
-	"golang.org/x/image/draw"
-
 	_ "golang.org/x/image/webp" // for processing webp images
+	_ "image/gif"               // for processing gif images
+	_ "image/jpeg"              // for processing jpeg images
+
+	"golang.org/x/image/draw"
 )
 
 // DefaultAvatarSize is the target CSS pixel size for avatar generation. It is

modules/graceful/manager_windows.go

@@ -1,5 +1,6 @@
 // Copyright 2019 The Gitea Authors. All rights reserved.
 // SPDX-License-Identifier: MIT
+
 // This code is heavily inspired by the archived gofacebook/gracenet/net.go handler
 
 //go:build windows

modules/migration/schemas_bindata.go

@@ -12,10 +12,10 @@ import (
 	"path"
 	"sync"
 
-	_ "embed"
-
 	"code.gitea.io/gitea/modules/assetfs"
 
+	_ "embed"
+
 	"github.com/santhosh-tekuri/jsonschema/v6"
 )
 

modules/options/options_bindata.go

@@ -10,9 +10,9 @@ package options
 import (
 	"sync"
 
-	_ "embed"
-
 	"code.gitea.io/gitea/modules/assetfs"
+
+	_ "embed"
 )
 
 //go:embed bindata.dat

modules/session/redis.go

@@ -1,18 +1,6 @@
 // Copyright 2013 Beego Authors
 // Copyright 2014 The Macaron Authors
 // Copyright 2020 The Gitea Authors. All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License"): you may
-// not use this file except in compliance with the License. You may obtain
-// a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-// License for the specific language governing permissions and limitations
-// under the License.
 // SPDX-License-Identifier: Apache-2.0
 
 package session

modules/templates/templates_bindata.go

@@ -10,9 +10,9 @@ package templates
 import (
 	"sync"
 
-	_ "embed"
-
 	"code.gitea.io/gitea/modules/assetfs"
+
+	_ "embed"
 )
 
 //go:embed bindata.dat