Pass ServeHeaderOptions by value instead of pointer, fine tune httplib tests (#36982)

Pass `ServeHeaderOptions` by value instead of pointer across all call
sites — no nil-check semantics are needed and the struct is small enough
that copying is fine.

## Changes

- **`services/context/base.go`**: `SetServeHeaders` and `ServeContent`
accept `ServeHeaderOptions` (value, not pointer); internal unsafe
pointer cast replaced with a clean type conversion
- **`routers/api/packages/helper/helper.go`**: `ServePackageFile`
variadic changed from `...*context.ServeHeaderOptions` to
`...context.ServeHeaderOptions`; internal variable is now a value type
- **All call sites** (13 files): `&context.ServeHeaderOptions{...}` →
`context.ServeHeaderOptions{...}`

Before/after at the definition level:
```go
// Before
func (b *Base) SetServeHeaders(opt *ServeHeaderOptions) { ... }
func (b *Base) ServeContent(r io.ReadSeeker, opts *ServeHeaderOptions) { ... }
func ServePackageFile(..., forceOpts ...*context.ServeHeaderOptions) { ... }

// After
func (b *Base) SetServeHeaders(opts ServeHeaderOptions) { ... }
func (b *Base) ServeContent(r io.ReadSeeker, opts ServeHeaderOptions) { ... }
func ServePackageFile(..., forceOpts ...context.ServeHeaderOptions) { ... }
```

---------

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>

services/context/base.go

@@ -170,15 +170,15 @@ func (b *Base) Redirect(location string, status ...int) {
 	http.Redirect(b.Resp, b.Req, location, code)
 }
 
-type ServeHeaderOptions httplib.ServeHeaderOptions
+type ServeHeaderOptions = httplib.ServeHeaderOptions
 
-func (b *Base) SetServeHeaders(opt *ServeHeaderOptions) {
-	httplib.ServeSetHeaders(b.Resp, *(*httplib.ServeHeaderOptions)(opt))
+func (b *Base) SetServeHeaders(opts ServeHeaderOptions) {
+	httplib.ServeSetHeaders(b.Resp, opts)
 }
 
 // ServeContent serves content to http request
-func (b *Base) ServeContent(r io.ReadSeeker, opts *ServeHeaderOptions) {
-	httplib.ServeSetHeaders(b.Resp, *(*httplib.ServeHeaderOptions)(opts))
+func (b *Base) ServeContent(r io.ReadSeeker, opts ServeHeaderOptions) {
+	httplib.ServeSetHeaders(b.Resp, opts)
 	http.ServeContent(b.Resp, b.Req, opts.Filename, opts.LastModified, r)
 }
 

services/repository/archiver/archiver.go

@@ -359,7 +359,7 @@ func ServeRepoArchive(ctx *gitea_context.Base, archiveReq *ArchiveRequest) error
 	}
 	defer fr.Close()
 
-	ctx.ServeContent(fr, &gitea_context.ServeHeaderOptions{
+	ctx.ServeContent(fr, gitea_context.ServeHeaderOptions{
 		Filename:     downloadName,
 		LastModified: archiver.CreatedUnix.AsLocalTime(),
 	})