Delete orders + federation sx_components.py — rendering inlined to routes

Phase 2 (Orders):
- Checkout error/return renders moved directly into route handlers
- Removed orphaned test_sx_helpers.py

Phase 3 (Federation):
- Auth pages use _render_social_auth_page() helper in routes
- Choose-username render inlined into identity routes
- Timeline/search/follow/interaction renders inlined into social routes
  using serializers imported from sxc.pages
- Added _social_page() to sxc/pages/__init__.py for shared use
- Home page renders inline in app.py

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

federation/sxc/pages/__init__.py

@@ -125,6 +125,23 @@ def _serialize_remote_actor(a) -> dict:
     }
 
 
+async def _social_page(ctx: dict, actor, *, content: str,
+                       title: str = "Rose Ash", meta_html: str = "") -> str:
+    """Build a full social page with social header."""
+    from shared.sx.helpers import render_to_sx, root_header_sx, header_child_sx, full_page_sx
+    from shared.sx.parser import SxExpr
+    from markupsafe import escape
+
+    actor_data = _serialize_actor(actor)
+    nav = await render_to_sx("federation-social-nav", actor=actor_data)
+    social_hdr = await render_to_sx("federation-social-header", nav=SxExpr(nav))
+    hdr = await root_header_sx(ctx)
+    child = await header_child_sx(social_hdr)
+    header_rows = "(<> " + hdr + " " + child + ")"
+    return await full_page_sx(ctx, header_rows=header_rows, content=content,
+                          meta_html=meta_html or f'<title>{escape(title)}</title>')
+
+
 def _get_actor():
     """Return current user's actor or None."""
     from quart import g