HS: disable-scripting security attribute (+1 test)

Add hs-scripting-disabled? helper that walks the ancestor chain checking
for the disable-scripting attribute. Guard hs-activate! with this check.
Add disable-scripting to generator BOOL_ATTRS so the attribute is emitted
in generated test setup code. Regen'd spec.

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

tests/playwright/generate-sx-tests.py

@@ -399,7 +399,8 @@ def parse_html(html):
                 'children': [], 'parent_idx': None
             }
             BOOL_ATTRS = {'checked', 'selected', 'disabled', 'multiple',
-                          'required', 'readonly', 'autofocus', 'hidden', 'open'}
+                          'required', 'readonly', 'autofocus', 'hidden', 'open',
+                          'disable-scripting'}
             for name, val in attrs:
                 if name == 'id': el['id'] = val
                 elif name == 'class': el['classes'] = (val or '').split()