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`.

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

templates/repo/diff/conversation.tmpl

@@ -9,7 +9,7 @@
 	<div class="conversation-holder" data-path="{{$comment.TreePath}}" data-side="{{if lt $comment.Line 0}}left{{else}}right{{end}}" data-idx="{{$comment.UnsignedLine}}">
 		{{if $resolved}}
 			<div class="resolved-placeholder">
-				<div class="flex-text-block tw-flex-wrap grey text">
+				<div class="flex-text-block tw-flex-wrap tw-text-text-light">
 					{{svg "octicon-check"}}
 					<b>{{$resolveDoer.Name}}</b> {{ctx.Locale.Tr "repo.issues.review.resolved_by"}}
 					{{if $invalid}}