refactor: use named Permission field in Repository struct instead of anonymous embedding (#37441)

The `Repository` struct in `services/context/repo.go` embedded
`access_model.Permission` anonymously, causing all permission methods to
be promoted directly onto `Repository`. This made it unclear at call
sites whether a method belonged to `Repository` itself or to its
embedded `Permission`.

### Changes

- **`services/context/repo.go`**: Replace anonymous
`access_model.Permission` with named field `Permission
access_model.Permission`
- **49 files** updated to route permission method calls through the
named field:

```go
// Before
ctx.Repo.IsAdmin()
ctx.Repo.CanWrite(unit.TypeCode)
ctx.Repo.CanReadIssuesOrPulls(isPull)
slices.ContainsFunc(unitTypes, ctx.Repo.CanWrite)

// After
ctx.Repo.Permission.IsAdmin()
ctx.Repo.Permission.CanWrite(unit.TypeCode)
ctx.Repo.Permission.CanReadIssuesOrPulls(isPull)
slices.ContainsFunc(unitTypes, ctx.Repo.Permission.CanWrite)
```

Methods defined directly on `*Repository` (`CanWriteToBranch`,
`CanCreateBranch`, etc.) are unchanged.

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: wxiaoguang <2114189+wxiaoguang@users.noreply.github.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Nicolas <bircni@icloud.com>

routers/web/repo/view.go

@@ -139,7 +139,7 @@ func loadLatestCommitData(ctx *context.Context, latestCommit *git.Commit) bool {
 		if err != nil {
 			log.Error("GetLatestCommitStatus: %v", err)
 		}
-		if !ctx.Repo.CanRead(unit_model.TypeActions) {
+		if !ctx.Repo.Permission.CanRead(unit_model.TypeActions) {
 			git_model.CommitStatusesHideActionsURL(ctx, statuses)
 		}
 
@@ -174,12 +174,11 @@ func markupRenderToHTML(ctx *context.Context, renderCtx *markup.RenderContext, r
 }
 
 func checkHomeCodeViewable(ctx *context.Context) {
-	if ctx.Repo.HasUnits() {
+	if ctx.Repo.Permission.HasUnits() {
 		if ctx.Repo.Repository.IsBeingCreated() {
 			task, err := admin_model.GetMigratingTask(ctx, ctx.Repo.Repository.ID)
 			if err != nil {
 				if admin_model.IsErrTaskDoesNotExist(err) {
-					ctx.Data["Repo"] = ctx.Repo
 					ctx.Data["CloneAddr"] = ""
 					ctx.Data["Failed"] = true
 					ctx.HTML(http.StatusOK, tplMigrating)
@@ -194,7 +193,6 @@ func checkHomeCodeViewable(ctx *context.Context) {
 				return
 			}
 
-			ctx.Data["Repo"] = ctx.Repo
 			ctx.Data["MigrateTask"] = task
 			ctx.Data["CloneAddr"], _ = util.SanitizeURL(cfg.CloneAddr)
 			ctx.Data["Failed"] = task.Status == structs.TaskStatusFailed