Port templates to NodeBB 4.14 benchpress escaping (#19)

NodeBB 4.14 turned on real HTML escaping for single-brace template interpolations (4.13 used an identity escape). This ports raw-HTML output to the double-brace forms ({{helper(...)}}, {{txEscape(content)}}, {{tx(name)}}), mirroring the harmony 2.2.72 -> 3.0.15 and core 4.13.2 -> 4.14.0 template diffs. Fixes the escaped-markup breakage on westgate.pw after the 2026.07.11-1 deploy.

Verified on a fresh 4.14.0 dev stack: no escaped tags on /, /categories, /category/2, /topic/1, /search; contract tests pass.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: vickydotbat <vickydotbat@tutamail.com>
Reviewed-on: #19
Reviewed-by: xtul <mpiasecki720@protonmail.com>
Co-authored-by: gitea-bot <gitea-bot@noreply.git.westgate.pw>
Co-committed-by: gitea-bot <gitea-bot@noreply.git.westgate.pw>

templates/emails/notification.tpl

@@ -20,7 +20,7 @@
 <tr class="notification-body">
 <td style="padding: 20px 40px; font-family: Jost, system-ui, -apple-system, 'Segoe UI', Roboto, Arial, sans-serif; font-size: 15px; line-height: 20px; color: #3a3340;">
 <p style="margin: 0; padding: 6px 0px; font-family: Jost, system-ui, -apple-system, 'Segoe UI', Roboto, Arial, sans-serif; font-size: 13px; line-height: 26px; color: #3a3340;">
-{body}
+{{txEscape(body)}}
 </p>
 </td>
 </tr>