Move SX docs rendering from sx_components.py to sxc/pages (phase 8)

Consolidate 86 component rendering functions into sxc/pages/__init__.py,
update 37 import sites in routes.py, remove app.py side-effect imports,
and delete sx/sxc/sx_components.py.

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

sx/app.py

@@ -1,7 +1,5 @@
 from __future__ import annotations
 import path_setup  # noqa: F401
-import sxc.sx_components as sx_components  # noqa: F401
-
 from shared.infrastructure.factory import create_base_app
 
 from bp import register_pages
@@ -48,8 +46,6 @@ def create_app() -> "Quart":
         domain_services_fn=register_domain_services,
     )
 
-    import sxc.sx_components  # noqa: F401
-
     from sxc.pages import setup_sx_pages
     setup_sx_pages()