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>

shared/browser/templates/_types/root/_head.html

@@ -6,7 +6,7 @@
     <link rel="stylesheet" type="text/css" href="{{asset_url('styles/blog-content.css')}}">
     
     <meta name="csrf-token" content="{{ csrf_token() }}">
-    <link rel="stylesheet" type="text/css" href="{{asset_url('styles/tw.css')}}">
+    <script src="https://cdn.tailwindcss.com?plugins=typography"></script>
     <link rel="stylesheet" href="{{asset_url('fontawesome/css/all.min.css')}}">
     <link rel="stylesheet" href="{{asset_url('fontawesome/css/v4-shims.min.css')}}">
     <link href="https://unpkg.com/prismjs/themes/prism.css" rel="stylesheet" />