Convert test/cart/blog/market layouts to use _ctx_to_env + render_to_sx_with_env

Phase 4 (Test): Update ~test-layout-full and ~test-detail-layout-full defcomps
to use ~root-header with env free variables. Switch render functions to
render_to_sx_with_env.

Phase 5 (Cart): Convert cart-page, cart-admin, and order render functions.
Update cart .sx layout defcomps to use ~root-header from free variables.

Phase 6 (Blog): Convert all 7 blog layouts (blog, settings, sub-settings x5).
Remove all root_header_sx calls from blog.

Phase 7 (Market): Convert market and market-admin layouts plus browse/product
render functions. Remove root_header_sx import.

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

market/sx/layouts.sx

@@ -0,0 +1,50 @@
+;; Market layout defcomps — root header from env free variables,
+;; market-specific headers passed as &key params.
+
+;; --- Browse layout: root + post header + market header ---
+
+(defcomp ~market-browse-layout-full (&key post-header market-header)
+  (<> (~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)
+    (~header-child-sx :inner (<> post-header market-header))))
+
+(defcomp ~market-browse-layout-oob (&key oob-header post-header-oob clear-oob)
+  (<> oob-header post-header-oob clear-oob))
+
+;; --- Product layout: root + post + market + product ---
+
+(defcomp ~market-product-layout-full (&key post-header market-header product-header)
+  (<> (~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)
+    (~header-child-sx :inner (<> post-header market-header product-header))))
+
+;; --- Product admin layout: root + post + market + product + admin ---
+
+(defcomp ~market-product-admin-layout-full (&key post-header market-header product-header admin-header)
+  (<> (~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)
+    (~header-child-sx :inner (<> post-header market-header product-header admin-header))))
+
+;; --- Market admin layout: root + post + market + market-admin ---
+
+(defcomp ~market-admin-layout-full (&key post-header market-header admin-header)
+  (<> (~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)
+    (~header-child-sx :inner (<> post-header market-header admin-header))))
+
+(defcomp ~market-admin-layout-oob (&key market-header-oob admin-oob-header clear-oob)
+  (<> market-header-oob admin-oob-header clear-oob))
+
+;; --- OOB wrappers ---
+
+(defcomp ~market-oob-wrap (&key parts)
+  (<> parts))
+
+;; --- Content wrappers ---
+
+(defcomp ~market-content-padded (&key content)
+  (<> content (div :class "pb-8")))