Fix CodeQL code scanning alerts (#36858)

Fixes 10 CodeQL code scanning alerts:

- Change `NewPagination`/`SetLinkHeader` to accept `int64` for total
count, clamping internally to fix incorrect-integer-conversion alerts
([#110](https://github.com/go-gitea/gitea/security/code-scanning/110),
[#114](https://github.com/go-gitea/gitea/security/code-scanning/114),
[#115](https://github.com/go-gitea/gitea/security/code-scanning/115),
[#116](https://github.com/go-gitea/gitea/security/code-scanning/116))
- Use `strconv.Atoi()` in `htmlrenderer.go` to avoid int64 intermediate
([#105](https://github.com/go-gitea/gitea/security/code-scanning/105),
[#106](https://github.com/go-gitea/gitea/security/code-scanning/106))
- Clamp regex match indices in `escape_stream.go` to fix
allocation-size-overflow
([#161](https://github.com/go-gitea/gitea/security/code-scanning/161),
[#162](https://github.com/go-gitea/gitea/security/code-scanning/162),
[#163](https://github.com/go-gitea/gitea/security/code-scanning/163))
- Cap slice pre-allocation in `GetIssueDependencies`
([#181](https://github.com/go-gitea/gitea/security/code-scanning/181))

---------

Co-authored-by: Claude (Opus 4.6) <noreply@anthropic.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

routers/web/repo/view.go

@@ -345,7 +345,7 @@ func RenderUserCards(ctx *context.Context, total int, getter func(opts db.ListOp
 	if page <= 0 {
 		page = 1
 	}
-	pager := context.NewPagination(total, setting.ItemsPerPage, page, 5)
+	pager := context.NewPagination(int64(total), setting.ItemsPerPage, page, 5)
 	ctx.Data["Page"] = pager
 
 	items, err := getter(db.ListOptions{
@@ -403,7 +403,7 @@ func Forks(ctx *context.Context) {
 		return
 	}
 
-	pager := context.NewPagination(int(total), pageSize, page, 5)
+	pager := context.NewPagination(total, pageSize, page, 5)
 	ctx.Data["ShowRepoOwnerAvatar"] = true
 	ctx.Data["ShowRepoOwnerOnList"] = true
 	ctx.Data["Page"] = pager