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/milestones.tmpl

@@ -57,7 +57,7 @@
 									{{ctx.Locale.Tr "repo.milestones.closed" $closedDate}}
 								{{else}}
 									{{if .DeadlineString}}
-										<span class="flex-text-inline {{if .IsOverdue}}text red{{end}}">
+										<span class="flex-text-inline {{if .IsOverdue}}tw-text-red{{end}}">
 											{{svg "octicon-calendar" 14}}
 											{{DateUtils.AbsoluteShort (.DeadlineString|DateUtils.ParseLegacy)}}
 										</span>
@@ -76,7 +76,7 @@
 								{{else}}
 									<a class="link-action flex-text-inline" href data-url="{{$.Link}}/{{.ID}}/close">{{svg "octicon-x" 14}}{{ctx.Locale.Tr "repo.milestones.close"}}</a>
 								{{end}}
-								<a class="link-action flex-text-inline text red" href data-modal-confirm="#repo-milestone-delete-modal" data-url="{{$.RepoLink}}/milestones/delete?id={{.ID}}">{{svg "octicon-trash" 14}}{{ctx.Locale.Tr "repo.issues.label_delete"}}</a>
+								<a class="link-action flex-text-inline tw-text-red" href data-modal-confirm="#repo-milestone-delete-modal" data-url="{{$.RepoLink}}/milestones/delete?id={{.ID}}">{{svg "octicon-trash" 14}}{{ctx.Locale.Tr "repo.issues.label_delete"}}</a>
 							</div>
 						{{end}}
 					</div>