fix(nav): Add trailing slash to pagination nav links (#17516)

## DESCRIBE YOUR PR

Addresses user feedback from docs.sentry.io (DOCS-AMX): "All previous
and next links are missing a trailing slash."

The `PaginationNav` component (previous/next page links at the bottom of
docs pages) was generating hrefs as `/${node.path}` without a trailing
slash. This was inconsistent with sidebar navigation links, which
correctly include a trailing slash (`'/' + node.path + '/'`).

- Changed `href={`/${node.path}`}` to `href={`/${node.path}/`}` in
`src/components/paginationNav.tsx`

## IS YOUR CHANGE URGENT?

- [x] None: Not urgent, can wait up to 1 week+

## PRE-MERGE CHECKLIST

- [ ] Checked Vercel preview for correctness, including links
- [ ] PR was reviewed and approved by any necessary SMEs
- [ ] PR was reviewed and approved by a member of the docs team

<div><a
href="https://cursor.com/agents/bc-24b9e842-e134-49a5-b001-106a55a841c0"><picture><source
media="(prefers-color-scheme: dark)"
srcset="https://cursor.com/assets/images/open-in-web-dark.png"><source
media="(prefers-color-scheme: light)"
srcset="https://cursor.com/assets/images/open-in-web-light.png"><img
alt="Open in Web" width="114" height="28"
src="https://cursor.com/assets/images/open-in-web-dark.png"></picture></a>&nbsp;<a
href="https://cursor.com/automations/ed76aa5d-e6c6-4626-bce4-30117ff0e2de"><picture><source
media="(prefers-color-scheme: dark)"
srcset="https://cursor.com/assets/images/view-automation-dark.png"><source
media="(prefers-color-scheme: light)"
srcset="https://cursor.com/assets/images/view-automation-light.png"><img
alt="View Automation" width="141" height="28"
src="https://cursor.com/assets/images/view-automation-dark.png"></picture></a>&nbsp;</div>

---------

Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: Sergiy Dybskiy <s@serg.tech>

Author: 3 people

src/components/paginationNav.tsx

@@ -8,8 +8,9 @@ export function PaginationNav({
   node: PaginationNavNode;
   title: 'Previous' | 'Next';
 }) {
+  const href = node.path === '' || node.path === '/' ? '/' : `/${node.path}/`;
   return (
-    <a href={`/${node.path}`} className="no-underline">
+    <a href={href} className="no-underline">
       <div
         className={`py-3 px-4 border-2 dark:[border-color:var(--gray-4)]  rounded-md transition-colors hover:[border-color:var(--accent)] ${
           title === 'Previous' ? 'text-left' : 'text-right'