Refine events + sx sub-module imports from background agents

Events: route imports now point to specific sub-modules (entries,
tickets, slots) instead of all going through renders.py. Merged
layouts into helpers.py. __init__.py now 20 lines.

SX Docs: moved dispatchers from helpers.py into essays.py, cleaned
up __init__.py to 24 lines.

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

events/bp/calendar/routes.py

@@ -224,7 +224,7 @@ def register():
 
         if post_data:
             from shared.services.entry_associations import get_associated_entries
-            from sxc.pages.renders import render_post_nav_entries_oob
+            from sxc.pages.entries import render_post_nav_entries_oob
 
             post_id = (post_data.get("post") or {}).get("id")
             cals = (