refactor: use WithRepo instead of WithDir for most git operations, clean up model migrations (#38555)

by the way, remove some unnecessary "models" imports from model
migration package, fix migration test model init bug
(modelmigration/migrationtest/tests.go)

models/db/engine.go

@@ -116,6 +116,10 @@ func RegisterModel(bean any, initFunc ...func() error) {
 	}
 }
 
+func ResetModels() {
+	registeredModels, registeredInitFuncs = nil, nil
+}
+
 // SyncAllTables sync the schemas of all tables, is required by unit test code
 func SyncAllTables() error {
 	_, err := xormEngine.StoreEngine("InnoDB").SyncWithOptions(xorm.SyncOptions{

models/init.go

@@ -0,0 +1,15 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package models
+
+import (
+	"context"
+
+	"gitea.dev/models/unit"
+)
+
+// Init initialize model
+func Init(ctx context.Context) error {
+	return unit.LoadUnitConfig()
+}

models/repostats/main_test.go

@@ -1,7 +1,7 @@
 // Copyright 2020 The Gitea Authors. All rights reserved.
 // SPDX-License-Identifier: MIT
 
-package models
+package repostats
 
 import (
 	"testing"

models/repostats/repo.go

@@ -2,7 +2,7 @@
 // Copyright 2017 The Gitea Authors. All rights reserved.
 // SPDX-License-Identifier: MIT
 
-package models
+package repostats
 
 import (
 	"context"
@@ -12,7 +12,6 @@ import (
 	"gitea.dev/models/db"
 	issues_model "gitea.dev/models/issues"
 	repo_model "gitea.dev/models/repo"
-	"gitea.dev/models/unit"
 	user_model "gitea.dev/models/user"
 	"gitea.dev/modules/log"
 
@@ -21,11 +20,6 @@ import (
 	"xorm.io/builder"
 )
 
-// Init initialize model
-func Init(ctx context.Context) error {
-	return unit.LoadUnitConfig()
-}
-
 type repoChecker struct {
 	querySQL   func(ctx context.Context) ([]int64, error)
 	correctSQL func(ctx context.Context, id int64) error

models/repostats/repo_test.go

@@ -1,7 +1,7 @@
 // Copyright 2017 The Gitea Authors. All rights reserved.
 // SPDX-License-Identifier: MIT
 
-package models
+package repostats
 
 import (
 	"testing"