Refactor SX templates: shared components, Python migration, cleanup

- Extract shared components (empty-state, delete-btn, sentinel, crud-*,
  view-toggle, img-or-placeholder, avatar, sumup-settings-form, auth
  forms, order tables/detail/checkout)
- Migrate all Python sx_call() callers to use shared components directly
- Remove 55+ thin wrapper defcomps from domain .sx files
- Remove trivial passthrough wrappers (blog-header-label, market-card-text, etc)
- Unify duplicate auth flows (account + federation) into shared/sx/templates/auth.sx
- Unify duplicate order views (cart + orders) into shared/sx/templates/orders.sx
- Disable static file caching in dev (SEND_FILE_MAX_AGE_DEFAULT=0)
- Add SX response validation and debug headers

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

market/sx/cards.sx

@@ -19,9 +19,6 @@
       (when labels (ul :class "flex flex-row gap-1" (map (lambda (l) (li l)) labels)))
       (div :class "text-stone-900 text-center line-clamp-3 break-words [overflow-wrap:anywhere]" brand))))
 
-(defcomp ~market-card-label-item (&key label)
-  (li label))
-
 (defcomp ~market-card-sticker (&key src name ring-cls)
   (img :src src :alt name :class (str "w-6 h-6" ring-cls)))
 
@@ -32,15 +29,9 @@
 (defcomp ~market-card-highlight (&key pre mid post)
   (<> pre (mark mid) post))
 
-(defcomp ~market-card-text (&key text)
-  (<> text))
-
-;; Price — single component accepts both prices, renders correctly
+;; Price — delegates to shared ~price
 (defcomp ~market-card-price (&key special-price regular-price)
-  (div :class "mt-1 flex items-baseline gap-2 justify-center"
-    (when special-price (div :class "text-lg font-semibold text-emerald-700" special-price))
-    (when (and special-price regular-price) (div :class "text-sm line-through text-stone-500" regular-price))
-    (when (and (not special-price) regular-price) (div :class "mt-1 text-lg font-semibold" regular-price))))
+  (~price :special-price special-price :regular-price regular-price))
 
 ;; Main product card — accepts pure data, composes sub-components
 (defcomp ~market-product-card (&key href hx-select
@@ -104,31 +95,3 @@
       (if desc-content desc-content (when desc desc)))
     (if badge-content badge-content (when badge badge))))
 
-(defcomp ~market-sentinel-mobile (&key id next-url hyperscript)
-  (div :id id
-       :class "block md:hidden h-[60vh] opacity-0 pointer-events-none js-mobile-sentinel"
-       :sx-get next-url :sx-trigger "intersect once delay:250ms, sentinelmobile:retry"
-       :sx-swap "outerHTML"
-       :_ hyperscript
-       :role "status" :aria-live "polite" :aria-hidden "true"
-    (div :class "js-loading text-center text-xs text-stone-400" "loading...")
-    (div :class "js-neterr hidden text-center text-xs text-stone-400" "Retrying...")))
-
-(defcomp ~market-sentinel-desktop (&key id next-url hyperscript)
-  (div :id id
-       :class "hidden md:block h-4 opacity-0 pointer-events-none"
-       :sx-get next-url :sx-trigger "intersect once delay:250ms, sentinel:retry"
-       :sx-swap "outerHTML"
-       :_ hyperscript
-       :role "status" :aria-live "polite" :aria-hidden "true"
-    (div :class "js-loading text-center text-xs text-stone-400" "loading...")
-    (div :class "js-neterr hidden text-center text-xs text-stone-400" "Retrying...")))
-
-(defcomp ~market-sentinel-end ()
-  (div :class "col-span-full mt-4 text-center text-xs text-stone-400" "End of results"))
-
-(defcomp ~market-market-sentinel (&key id next-url)
-  (div :id id :class "h-4 opacity-0 pointer-events-none"
-       :sx-get next-url :sx-trigger "intersect once delay:250ms"
-       :sx-swap "outerHTML" :role "status" :aria-hidden "true"
-    (div :class "text-center text-xs text-stone-400" "loading...")))