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/search-results.tpl

@@ -23,7 +23,7 @@
 		<div class="post-body d-flex flex-column gap-1">
 			<div class="d-flex gap-3 post-info">
 				<div class="post-author d-flex gap-1">
-					<a class="lh-1 text-decoration-none" href="{config.relative_path}/user/{./user.userslug}">{buildAvatar(./user, "16px", true, "not-responsive")}</a>
+					<a class="lh-1 text-decoration-none" href="{config.relative_path}/user/{./user.userslug}">{{buildAvatar(./user, "16px", true, "not-responsive")}}</a>
 					<a class="fw-semibold text-sm" href="{config.relative_path}/user/{./user.userslug}">{../user.displayname}</a>
 				</div>
 				<span class="timeago text-sm text-muted" title="{./timestampISO}"></span>