Fix load_service_components path for sx, market, events

The load_service_components call used dirname twice from
sxc/pages/__init__.py, yielding {service}/sxc/ instead of
{service}/. This meant {service}/sx/*.sx files (layouts, calendar
components, etc.) were never loaded into the component env.

- sx: ~sx-layout-full not found → Unknown component on client
- events: ~events-calendar-grid not found → Unknown component
- market: also fix url_for endpoint for defpage_market_admin
  (mounted on app, not blueprint — no prefix needed)

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

events/sxc/pages/__init__.py

@@ -26,8 +26,9 @@ def _load_events_page_files() -> None:
     import os
     from shared.sx.pages import load_page_dir
     from shared.sx.jinja_bridge import load_service_components
-    base = os.path.dirname(os.path.dirname(__file__))
-    load_service_components(base, service_name="events")
+    sxc_dir = os.path.dirname(os.path.dirname(__file__))         # events/sxc/
+    service_root = os.path.dirname(sxc_dir)                       # events/
+    load_service_components(service_root, service_name="events")
     load_page_dir(os.path.dirname(__file__), "events")