Auto-mount defpages: eliminate Python route stubs across all 9 services

Defpages are now declared with absolute paths in .sx files and auto-mounted
directly on the Quart app, removing ~850 lines of blueprint mount_pages calls,
before_request hooks, and g.* wrapper boilerplate. A new page = one defpage
declaration, nothing else.

Infrastructure:
- async_eval awaits coroutine results from callable dispatch
- auto_mount_pages() mounts all registered defpages on the app
- g._defpage_ctx pattern passes helper data to layout context

Migrated: sx, account, orders, federation, cart, market, events, blog

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

account/bp/account/routes.py

@@ -8,15 +8,12 @@ from __future__ import annotations
 from quart import (
     Blueprint,
     request,
-    redirect,
     g,
 )
 from sqlalchemy import select
 
 from shared.models import UserNewsletter
-from shared.models.ghost_membership_entities import GhostNewsletter
-from shared.infrastructure.urls import login_url
-from shared.infrastructure.fragments import fetch_fragment, fetch_fragments
+from shared.infrastructure.fragments import fetch_fragments
 from shared.sx.helpers import sx_response
 
 
@@ -25,8 +22,7 @@ def register(url_prefix="/"):
 
     @account_bp.before_request
     async def _prepare_page_data():
-        """Fetch account_nav fragments and load data for defpage routes."""
-        # Fetch account nav items for layout (was in context_processor)
+        """Fetch account_nav fragments for layout."""
         events_nav, cart_nav, artdag_nav = await fetch_fragments([
             ("events", "account-nav-item", {}),
             ("cart", "account-nav-item", {}),
@@ -34,48 +30,6 @@ def register(url_prefix="/"):
         ], required=False)
         g.account_nav = events_nav + cart_nav + artdag_nav
 
-        if request.method != "GET":
-            return
-
-        endpoint = request.endpoint or ""
-
-        # Newsletters page — load newsletter data
-        if endpoint.endswith("defpage_newsletters"):
-            result = await g.s.execute(
-                select(GhostNewsletter).order_by(GhostNewsletter.name)
-            )
-            all_newsletters = result.scalars().all()
-
-            sub_result = await g.s.execute(
-                select(UserNewsletter).where(
-                    UserNewsletter.user_id == g.user.id,
-                )
-            )
-            user_subs = {un.newsletter_id: un for un in sub_result.scalars().all()}
-
-            newsletter_list = []
-            for nl in all_newsletters:
-                un = user_subs.get(nl.id)
-                newsletter_list.append({
-                    "newsletter": nl,
-                    "un": un,
-                    "subscribed": un.subscribed if un else False,
-                })
-            g.newsletters_data = newsletter_list
-
-        # Fragment page — load fragment from events service
-        elif endpoint.endswith("defpage_fragment_page"):
-            slug = request.view_args.get("slug")
-            if slug and g.get("user"):
-                fragment_html = await fetch_fragment(
-                    "events", "account-page",
-                    params={"slug": slug, "user_id": str(g.user.id)},
-                )
-                if not fragment_html:
-                    from quart import abort
-                    abort(404)
-                g.fragment_page_data = fragment_html
-
     @account_bp.post("/newsletter/<int:newsletter_id>/toggle/")
     async def toggle_newsletter(newsletter_id: int):
         if not g.get("user"):