Vertically center "Show Resolved" (#35211) (#35218)

Backport #35211 by @silverwind

Before, "Show Resolved" slightly off-center:

<img width="174" height="60" alt="Screenshot 2025-08-04 at 15 07 13"
src="https://github.com/user-attachments/assets/a165f721-4749-4ea3-bde0-141ad43a6142"
/>

After: centered:

<img width="176" height="63" alt="Screenshot 2025-08-04 at 15 07 22"
src="https://github.com/user-attachments/assets/f87e16bc-d067-4040-b940-9adb4cf182c1"
/>

Co-authored-by: silverwind <[email protected]>

Author: GiteaBot

templates/repo/issue/view_content/conversation.tmpl

@@ -15,7 +15,7 @@
 					</span>
 				{{end}}
 			</div>
-			<div>
+			<div class="tw-flex tw-items-center">
 				{{if or $invalid $resolved}}
 					<button id="show-outdated-{{$comment.ID}}" data-comment="{{$comment.ID}}" class="{{if not $resolved}}tw-hidden{{end}} btn tiny show-outdated">
 						{{svg "octicon-unfold" 16 "tw-mr-2"}}