Move market composition from Python to .sx defcomps (Phase 3)

Python sxc/pages/ functions no longer build nested sx_call chains or
reference leaf component names. Instead they extract data (URLs, prices,
CSRF, cart state) and call a single top-level composition defcomp with
pure data values. The .sx defcomps handle all component-to-component
wiring, iteration (map), and conditional rendering.

New .sx composition defcomps:
- headers.sx: ~market-header-from-data, ~market-desktop-nav-from-data,
  ~market-product-header-from-data, ~market-product-admin-header-from-data
- prices.sx: ~market-prices-header-from-data, ~market-card-price-from-data
- navigation.sx: ~market-mobile-nav-from-data
- cards.sx: ~market-product-cards-content, ~market-card-from-data,
  ~market-cards-content, ~market-landing-from-data
- detail.sx: ~market-product-detail-from-data, ~market-detail-gallery-from-data,
  ~market-detail-info-from-data
- meta.sx: ~market-product-meta-from-data
- filters.sx: ~market-desktop-filter-from-data, ~market-mobile-chips-from-data,
  ~market-mobile-filter-content-from-data, plus 6 sub-composition defcomps

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

market/sx/navigation.sx

@@ -61,3 +61,37 @@
 (defcomp ~market-mobile-cat-details (&key open summary subs)
   (details :class "group/cat py-1" :open open
     summary subs))
+
+
+;; ---------------------------------------------------------------------------
+;; Composition: mobile nav panel from pre-computed category data
+;; ---------------------------------------------------------------------------
+
+(defcomp ~market-mobile-nav-from-data (&key categories all-href all-active hx-select select-colours)
+  (~market-mobile-nav-wrapper :items
+    (<>
+      (~market-mobile-all-link :href all-href :hx-select hx-select
+         :active all-active :select-colours select-colours)
+      (map (lambda (cat)
+        (~market-mobile-cat-details
+          :open (get cat "active")
+          :summary (~market-mobile-cat-summary
+            :bg-cls (if (get cat "active") " bg-stone-900 text-white hover:bg-stone-900" "")
+            :href (get cat "href") :hx-select hx-select
+            :select-colours select-colours :cat-name (get cat "name")
+            :count-label (str (get cat "count") " products")
+            :count-str (str (get cat "count"))
+            :chevron (~market-mobile-chevron))
+          :subs (if (get cat "subs")
+            (~market-mobile-subs-panel :links
+              (<> (map (lambda (sub)
+                (~market-mobile-sub-link
+                  :select-colours select-colours
+                  :active (get sub "active")
+                  :href (get sub "href") :hx-select hx-select
+                  :label (get sub "label")
+                  :count-label (str (get sub "count") " products")
+                  :count-str (str (get sub "count"))))
+                (get cat "subs"))))
+            (~market-mobile-view-all :href (get cat "href") :hx-select hx-select))))
+        categories))))