Refactor repo header/list (#29969)

1. Use general "mobile-only" and "not-mobile" CSS styles, remove some`@media (max-width: 767.98px)` tricks
2. Use `CountFmt` for repo list, just like the repo header (and it matches GitHub, to avoid big numbers bloat the page)

(cherry picked from commit bfa160fc98a23923b6ce1cd4d99e8970d937d6ec)

Conflicts:
	templates/explore/repo_list.tmpl
	templates/repo/header.tmpl
	web_src/css/repo/header.css

 Resolved the template conflicts by porting the changes to Forgejo (in
 case of `header.tmpl`, applying the changes in `header_fork.tmpl). In
 case of the CSS change, opted to take Gitea's version and drop the
 entire media query.

options/locale/locale_en-US.ini

@@ -1083,6 +1083,7 @@ watchers = Watchers
 stargazers = Stargazers
 stars_remove_warning = This will remove all stars from this repository.
 forks = Forks
+stars = Stars
 reactions_more = and %d more
 unit_disabled = The site administrator has disabled this repository section.
 language_other = Other
@@ -3008,9 +3009,6 @@ repos.unadopted.no_more = No more unadopted repositories found
 repos.owner = Owner
 repos.name = Name
 repos.private = Private
-repos.watches = Watches
-repos.stars = Stars
-repos.forks = Forks
 repos.issues = Issues
 repos.size = Size
 repos.lfs_size = LFS Size