Refactor text utility classes to Tailwind CSS (#36703)

Replace Fomantic/custom CSS text utility classes with their Tailwind
equivalents:

- `.text.<color>` compound classes → `tw-text-<color>` classes
- `.text.small` (`font-size: 0.75em`) → `tw-text-xs` (11px)
- `.text.truncate` (`overflow-x: hidden; text-overflow: ellipsis;
white-space: nowrap; display: inline-block`) → `tw-inline-block
tw-truncate`

Remove the now-unused CSS rules from `base.css` and `dashboard.css`.

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

templates/repo/issue/view_content.tmpl

@@ -16,11 +16,11 @@
 					<div class="comment-header avatar-content-left-arrow" role="heading" aria-level="3">
 						<div class="comment-header-left">
 							{{if .Issue.OriginalAuthor}}
-								<span class="text black tw-font-semibold">
+								<span class="tw-text-text tw-font-semibold">
 									{{svg (MigrationIcon .Repository.GetOriginalURLHostname)}}
 									{{.Issue.OriginalAuthor}}
 								</span>
-								<span class="text grey muted-links">
+								<span class="tw-text-text-light muted-links">
 									{{ctx.Locale.Tr "repo.issues.commented_at" .Issue.HashTag $createdStr}}
 								</span>
 								<span class="text migrate">
@@ -30,7 +30,7 @@
 								<a class="inline-timeline-avatar" href="{{.Issue.Poster.HomeLink}}">
 									{{ctx.AvatarUtils.Avatar .Issue.Poster 24}}
 								</a>
-								<span class="text grey muted-links">
+								<span class="tw-text-text-light muted-links">
 									{{template "shared/user/authorlink" .Issue.Poster}}
 									{{ctx.Locale.Tr "repo.issues.commented_at" .Issue.HashTag $createdStr}}
 								</span>