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/card.tmpl

@@ -22,7 +22,7 @@
 			{{end}}
 		</div>
 		<div class="meta">
-			<span class="text light grey muted-links">
+			<span class="tw-text-grey-light muted-links">
 				{{if not $.Page.Repository}}{{.Repo.FullName}}{{end}}#{{.Index}}
 				{{$timeStr := DateUtils.TimeSince .GetLastEventTimestamp}}
 				{{if .OriginalAuthor}}
@@ -46,8 +46,8 @@
 		{{range index $.Page.LinkedPRs .ID}}
 		<div class="meta tw-my-1">
 			<a href="{{.Repo.Link}}/pulls/{{.Index}}">
-				<span class="tw-m-0 text {{if .PullRequest.HasMerged}}purple{{else if .IsClosed}}red{{else}}green{{end}}">{{svg "octicon-git-merge" 16 "tw-mr-1 tw-align-middle"}}</span>
-				<span class="tw-align-middle">{{.Title}} <span class="text light grey">#{{.Index}}</span></span>
+				<span class="tw-m-0 {{if .PullRequest.HasMerged}}tw-text-purple{{else if .IsClosed}}tw-text-red{{else}}tw-text-green{{end}}">{{svg "octicon-git-merge" 16 "tw-mr-1 tw-align-middle"}}</span>
+				<span class="tw-align-middle">{{.Title}} <span class="tw-text-grey-light">#{{.Index}}</span></span>
 			</a>
 		</div>
 		{{end}}