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>

market/app.py

@@ -103,21 +103,16 @@ def create_app() -> "Quart":
     from sxc.pages import setup_market_pages
     setup_market_pages()
 
-    from shared.sx.pages import mount_pages
-
     # All markets: / — global view across all pages
     all_markets_bp = register_all_markets()
-    mount_pages(all_markets_bp, "market", names=["all-markets-index"])
     app.register_blueprint(all_markets_bp, url_prefix="/")
 
     # Page markets: /<slug>/ — markets for a single page
     page_markets_bp = register_page_markets()
-    mount_pages(page_markets_bp, "market", names=["page-markets-index"])
     app.register_blueprint(page_markets_bp, url_prefix="/<slug>")
 
     # Page admin: /<slug>/admin/ — post-level admin for markets
     page_admin_bp = register_page_admin()
-    mount_pages(page_admin_bp, "market", names=["page-admin"])
     app.register_blueprint(page_admin_bp, url_prefix="/<slug>/admin")
 
     # Market blueprint nested under post slug: /<page_slug>/<market_slug>/
@@ -135,6 +130,10 @@ def create_app() -> "Quart":
     app.register_blueprint(register_actions())
     app.register_blueprint(register_data())
 
+    # Auto-mount all defpages with absolute paths
+    from shared.sx.pages import auto_mount_pages
+    auto_mount_pages(app, "market")
+
     # --- Auto-inject slugs into url_for() calls ---
     @app.url_value_preprocessor
     def pull_slugs(endpoint, values):