Delete last sx_components.py files: relations + test (phase 9)

Move relations component loading into app.py. Move test rendering
functions to test/sxc/pages/__init__.py, update route imports, and
delete both sx_components.py files. Zero sx_components imports remain.

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

test/app.py

@@ -1,7 +1,5 @@
 from __future__ import annotations
 import path_setup  # noqa: F401
-import sx.sx_components as sx_components  # noqa: F401
-
 from shared.infrastructure.factory import create_base_app
 from shared.sx.jinja_bridge import render
 
@@ -36,7 +34,10 @@ def create_app() -> "Quart":
         domain_services_fn=register_domain_services,
     )
 
-    import sx.sx_components  # noqa: F401
+    # Load .sx components
+    import os
+    from shared.sx.jinja_bridge import load_service_components
+    load_service_components(os.path.dirname(__file__))
 
     app.register_blueprint(register_dashboard(url_prefix="/"))