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/sx/parser.py

@@ -138,6 +138,7 @@ class Tokenizer:
             content = content.replace("\\n", "\n")
             content = content.replace("\\t", "\t")
             content = content.replace('\\"', '"')
+            content = content.replace("\\/", "/")
             content = content.replace("\\\\", "\\")
             return content
 
@@ -284,6 +285,7 @@ def serialize(expr: Any, indent: int = 0, pretty: bool = False) -> str:
             .replace('"', '\\"')
             .replace("\n", "\\n")
             .replace("\t", "\\t")
+            .replace("</script", "<\\/script")
         )
         return f'"{escaped}"'