Port templates to NodeBB 4.14 benchpress escaping

NodeBB 4.14 registers a real __escape for template rendering (4.13 used
identity), so raw-HTML output must use the double-brace forms:
- HTML helpers: {{buildAvatar(...)}}, {{buildCategoryIcon(...)}}, etc.
- Pre-rendered HTML fields: {{txEscape(content)}} / {{./descriptionParsed}}
- Token-bearing text (nav labels, category names): {{tx(...)}}
- emails/partials/post-queue-body.tpl also adopts the 4.14 data shape
  (notification.category/topic/user/content).

Mirrors the harmony 2.2.72 -> 3.0.15 and core 4.13.2 -> 4.14.0 diffs.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

templates/partials/categories/children.tpl

@@ -3,7 +3,7 @@
 	{{{ if !./isSection }}}
 	<li data-cid="{./cid}" class="category-children-item small {./class}">
 		<div class="westgate-category-child d-flex gap-1">
-			{buildCategoryIcon(@value, "18px", "westgate-child-icon rounded-1")}
+			{{buildCategoryIcon(@value, "18px", "westgate-child-icon rounded-1")}}
 			<a href="{{{ if ./link }}}{./link}{{{ else }}}{config.relative_path}/category/{./slug}{{{ end }}}" class="text-reset fw-semibold flex-1">{./name}</a>
 		</div>
 	</li>