Replace env free-variable threading with IO-primitive auto-fetch macros

Layout components now self-resolve context (cart-mini, auth-menu, nav-tree,
rights, URLs) via new IO primitives (root-header-ctx, select-colours,
account-nav-ctx, app-rights) and defmacro wrappers (~root-header-auto,
~auth-header-row-auto, ~root-mobile-auto). This eliminates _ctx_to_env(),
HELPER_CSS_CLASSES, and verbose :key threading across all 10 services.

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

account/sx/layouts.sx

@@ -1,33 +1,20 @@
-;; Account layout defcomps — read ctx values from env free variables.
+;; Account layout defcomps — fully self-contained via IO primitives.
 ;; Registered via register_sx_layout("account", ...) in __init__.py.
-;; Free variables come from _ctx_to_env() in shared/sx/helpers.py.
 
 ;; Full page: root header + auth header row in header-child
 (defcomp ~account-layout-full ()
-  (<> (~root-header :cart-mini cart-mini :blog-url blog-url :site-title site-title
-                     :app-label app-label :nav-tree nav-tree :auth-menu auth-menu
-                     :nav-panel nav-panel :settings-url settings-url :is-admin is-admin)
+  (<> (~root-header-auto)
     (~header-child-sx
-      :inner (~auth-header-row :account-url account-url
-                                :select-colours select-colours
-                                :account-nav account-nav))))
+      :inner (~auth-header-row-auto))))
 
 ;; OOB (HTMX): auth row + root header, both with oob=true
 (defcomp ~account-layout-oob ()
-  (<> (~auth-header-row :account-url account-url
-                         :select-colours select-colours
-                         :account-nav account-nav
-                         :oob true)
-    (~root-header :cart-mini cart-mini :blog-url blog-url :site-title site-title
-                   :app-label app-label :nav-tree nav-tree :auth-menu auth-menu
-                   :nav-panel nav-panel :settings-url settings-url :is-admin is-admin
-                   :oob true)))
+  (<> (~auth-header-row-auto true)
+    (~root-header-auto true)))
 
 ;; Mobile menu: auth section + root nav
 (defcomp ~account-layout-mobile ()
   (<> (~mobile-menu-section
         :label "account" :href "/" :level 1 :colour "sky"
-        :items (~auth-nav-items :account-url account-url
-                                 :select-colours select-colours
-                                 :account-nav account-nav))
-    (~root-mobile :nav-tree nav-tree :auth-menu auth-menu)))
+        :items (~auth-nav-items-auto))
+    (~root-mobile-auto)))