refactor: replace Fomantic modal with native dialog (#39846)

Replace Fomantic's hard-forked jQuery modal with native `<dialog>`
elements, advancing https://github.com/go-gitea/gitea/issues/29849. The
UI is visually unchanged. Dialogs open with `show()` over an `inert`
page, so tooltips, popups and toasts mounted on `<body>` stay usable
above them, unlike with `showModal()`
(https://github.com/whatwg/html/issues/9936).

- Remove the Fomantic modal and dimmer, add `showModal` and `hideModal`
- Declare modals as `<dialog class="modal-dialog">`, shown inside a
`.modal-backdrop`, instead of `ui modal` with its unused size classes
- Remove two modals that could never be opened
- Block the page while a modal is open, close the topmost one on Escape
and restore focus to its opener
- Allow stacked modals, use a confirm modal instead of `window.confirm`
for deleting content history
- Hide popups and toasts when a modal opens or closes
- Keep the release notes modal open when generating notes fails

Fixes: https://github.com/go-gitea/gitea/issues/39643
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

templates/org/team/members.tmpl

@@ -72,13 +72,15 @@
 		</div>
 	</div>
 </div>
-<form class="ui small modal form-fetch-action" method="post" id="remove-team-member">
+<dialog class="modal-dialog" id="remove-team-member">
 	<div class="header">
 		{{ctx.Locale.Tr "org.members.remove"}}
 	</div>
-	<div class="content">
-		<p>{{ctx.Locale.Tr "org.members.remove.detail" (HTMLFormat `<span class="%s"></span>` "name") (HTMLFormat `<span class="%s"></span>` "team-name")}}</p>
-	</div>
-	{{template "base/modal_actions_confirm" .}}
-</form>
+	<form class="form-fetch-action" method="post">
+		<div class="content">
+			<p>{{ctx.Locale.Tr "org.members.remove.detail" (HTMLFormat `<span class="%s"></span>` "name") (HTMLFormat `<span class="%s"></span>` "team-name")}}</p>
+		</div>
+		{{template "base/modal_actions_confirm" .}}
+	</form>
+</dialog>
 {{template "base/footer" .}}

templates/org/team/new.tmpl

@@ -194,7 +194,7 @@
 	</div>
 </div>
 
-<div class="ui small modal" id="delete-team">
+<dialog class="modal-dialog" id="delete-team">
 	<div class="header">
 		{{svg "octicon-trash"}}
 		{{ctx.Locale.Tr "org.teams.delete_team_title"}}
@@ -203,5 +203,5 @@
 		<p>{{ctx.Locale.Tr "org.teams.delete_team_desc"}}</p>
 	</div>
 	{{template "base/modal_actions_confirm" .}}
-</div>
+</dialog>
 {{template "base/footer" .}}

templates/org/team/sidebar.tmpl

@@ -91,7 +91,7 @@
 		</div>
 	{{end}}
 </div>
-<div class="ui mini modal" id="org-member-leave-team">
+<dialog class="modal-dialog" id="org-member-leave-team">
 	<div class="header">
 		{{ctx.Locale.Tr "org.teams.leave"}}
 	</div>
@@ -99,4 +99,4 @@
 		<p>{{ctx.Locale.Tr "org.teams.leave.detail" (HTMLFormat `<span class="%s"></span>` "to-leave-team-name")}}</p>
 		{{template "base/modal_actions_confirm" .}}
 	</form>
-</div>
+</dialog>

templates/org/team/teams.tmpl

@@ -63,7 +63,7 @@
 	{{template "base/paginate" .}}
 	</div>
 </div>
-<div class="ui mini modal" id="org-member-leave-team">
+<dialog class="modal-dialog" id="org-member-leave-team">
 	<div class="header">
 		{{ctx.Locale.Tr "org.teams.leave"}}
 	</div>
@@ -71,5 +71,5 @@
 		<p>{{ctx.Locale.Tr "org.teams.leave.detail" (HTMLFormat `<span class="%s"></span>` "to-leave-team-name")}}</p>
 		{{template "base/modal_actions_confirm" .}}
 	</form>
-</div>
+</dialog>
 {{template "base/footer" .}}