feat(themes,templates,signup-gate): add signup gate, remove custom theme switcher from links footer

templates/custom/extra_links_footer.tmpl

@@ -1,14 +0,0 @@
-{{if .IsSigned}}
-<div class="item theme-selector-footer" style="margin-left: 15px;">
-  <form class="ui form" action="{{AppSubUrl}}/user/settings/appearance/theme" method="post">
-    <input type="hidden" name="_csrf" value="{{.CsrfToken}}">
-    <select name="theme" id="footer-theme-select" class="ui dropdown">
-      <option value="neogothic" {{if eq .SignedUser.Theme "neogothic"}}selected{{end}}>neogothic</option>
-      <option value="pinkie" {{if eq .SignedUser.Theme "pinkie"}}selected{{end}}>pinkie</option>
-      <option value="gitea-dark" {{if eq .SignedUser.Theme "gitea-dark"}}selected{{end}}>gitea-dark</option>
-      <option value="gitea-light" {{if eq .SignedUser.Theme "gitea-light"}}selected{{end}}>gitea-light</option>
-    </select>
-    <button type="submit" class="ui mini basic button">OK</button>
-  </form>
-</div>
-{{end}}

templates/user/auth/activate_prompt.tmpl

@@ -0,0 +1,18 @@
+{{template "base/head" .}}
+<div role="main" aria-label="{{.Title}}" class="page-content user activate">
+	<div class="ui middle very relaxed page grid">
+		<div class="column">
+			<h2 class="ui top attached header">
+				{{ctx.Locale.Tr "auth.active_your_account"}}
+			</h2>
+			<div class="ui attached segment">
+				{{template "base/alert" .}}
+				<p>{{.ActivationPromptMessage}}</p>
+				<div class="divider"></div>
+				<p>No email needed - activate the account yourself, it takes one click.</p>
+				<a class="ui primary button" href="{{AppSubUrl}}/activate">Activate my account</a>
+			</div>
+		</div>
+	</div>
+</div>
+{{template "base/footer" .}}