Fix markets admin link to market.rose-ash.com/{slug}/admin/

Markets use the same admin pattern as calendars but on the market
subdomain, not the events subdomain.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

blog/sexp/sexp_components.py

@@ -149,7 +149,7 @@ def _post_admin_nav_html(ctx: dict) -> str:
     if callable(events_url_fn):
         for url_fn, path, label in [
             (events_url_fn, f"/{slug}/admin/", "calendars"),
-            (market_url_fn, f"/{slug}/", "markets"),
+            (market_url_fn, f"/{slug}/admin/", "markets"),
             (events_url_fn, f"/{slug}/payments/", "payments"),
         ]:
             if not callable(url_fn):