Revert overflow: overlay (revert #21850) (#25231)

It causes not only one issue like #25221 (the footer width was also
affected by that change and was fixed some time ago)

The problem of "overflow: overlay" (#21850) is:

* It's not widely supported and is non-standard
https://caniuse.com/css-overflow-overlay
* It's not widely tested in Gitea (some standard layout like `ui
container + ui grid` may break it).
* The benefit seems smaller than the problems it brings.

So, I think it is good to revert it.

----

Let's leave enough time for testing and reviewing.

---------

Co-authored-by: Giteabot <teabot@gitea.io>
Co-authored-by: silverwind <me@silverwind.io>

web_src/fomantic/.npmrc

@@ -1,5 +1,7 @@
 audit=false
 fund=false
 update-notifier=false
-package-lock=false
+package-lock=true
+save-exact=true
+lockfile-version=3
 optional=false

web_src/fomantic/_site/globals/site.variables

@@ -8,3 +8,4 @@
 @variationPopupTooltip: false;
 @linkHoverUnderline: underline;
 @variationButtonSocial: false;
+@pageOverflowX: visible;

web_src/fomantic/build/semantic.css

@@ -24658,7 +24658,7 @@ html {
 body {
   margin: 0;
   padding: 0;
-  overflow-x: hidden;
+  overflow-x: visible;
   min-width: 320px;
   background: #FFFFFF;
   font-family: var(--fonts-regular);