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/commit_page.tmpl

@@ -140,11 +140,11 @@
 				{{end}}
 			</div>
 
-			<span class="text grey">{{DateUtils.TimeSince .Commit.Author.When}}</span>
+			<span class="tw-text-text-light">{{DateUtils.TimeSince .Commit.Author.When}}</span>
 
 			<div class="flex-text-inline">
 				{{if or (ne .Commit.Committer.Name .Commit.Author.Name) (ne .Commit.Committer.Email .Commit.Author.Email)}}
-					<span class="text grey">{{ctx.Locale.Tr "repo.diff.committed_by"}}</span>
+					<span class="tw-text-text-light">{{ctx.Locale.Tr "repo.diff.committed_by"}}</span>
 					{{if and .Verification.CommittingUser .Verification.CommittingUser.ID}}
 						{{ctx.AvatarUtils.Avatar .Verification.CommittingUser 20}}
 						<a href="{{.Verification.CommittingUser.HomeLink}}"><strong>{{.Commit.Committer.Name}}</strong></a>
@@ -192,7 +192,7 @@
 				{{else}}
 					<strong>{{.NoteCommit.Author.Name}}</strong>
 				{{end}}
-				<span class="text grey">{{DateUtils.TimeSince .NoteCommit.Author.When}}</span>
+				<span class="tw-text-text-light">{{DateUtils.TimeSince .NoteCommit.Author.When}}</span>
 			</div>
 			<div class="ui bottom attached info segment git-notes">
 				<pre class="commit-body">{{.NoteRendered | SanitizeHTML}}</pre>