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/quick-search-results.tpl

@@ -21,7 +21,7 @@
 		</a>
 		<div class="d-flex gap-2 post-info px-2 text-xs">
 			<div class="category-item d-inline-block ff-secondary">
-				{buildCategoryLabel(posts.category, "span")}
+				{{buildCategoryLabel(posts.category, "span")}}
 			</div>
 			<span class="timeago text-muted" title="{posts.timestampISO}"></span>
 		</div>