gerd.forgejo: now uses authelia for authentication + patches for signin

machines/gerd/services/forgejo/patches/signin-template.patch

@@ -0,0 +1,20 @@
+diff --git a/templates/user/auth/signin_inner.tmpl b/templates/user/auth/signin_inner.tmpl
+index 9872096fbc..1076f90326 100644
+--- a/templates/user/auth/signin_inner.tmpl
++++ b/templates/user/auth/signin_inner.tmpl
+@@ -10,6 +10,7 @@
+ </h4>
+ <div class="ui attached segment">
+ 	<form class="ui form tw-max-w-2xl tw-m-auto" action="{{.SignInLink}}" method="post">
++	<div {{if not .LinkAccountMode}}style="display:none;"{{end}}>
+ 	{{.CsrfTokenHtml}}
+ 	<div class="required field {{if and (.Err_UserName) (or (not .LinkAccountMode) (and .LinkAccountMode .LinkAccountModeSignIn))}}error{{end}}">
+ 		<label for="user_name">{{ctx.Locale.Tr "home.uname_holder"}}</label>
+@@ -53,6 +54,7 @@
+ 	<div class="divider divider-text">
+ 		{{ctx.Locale.Tr "sign_in_or"}}
+ 	</div>
++	</div>
+ 	<div id="oauth2-login-navigator" class="tw-py-1">
+ 		<div class="tw-flex tw-flex-col tw-justify-center">
+ 			<div id="oauth2-login-navigator-inner" class="tw-flex tw-flex-col tw-flex-wrap tw-items-center tw-gap-2">