Fix unquoted (code) element in SX manifesto essay

The (code :class "text-violet-700" ...) was embedded inside a string
child of (p), causing the SX parser to see text-violet-700 as a bare
symbol. Close the text string before the (code) element so it becomes
a proper child of the paragraph.

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

sx/sxc/pages/__init__.py

@@ -2620,8 +2620,8 @@ def _essay_sx_manifesto() -> str:
         'while insisting this was not inline styles.")'
         f'    {p}'
         '      "The s-expression resolves the CSS question by eliminating it. '
-        'Styles are expressions. '
-        f'  (code :class \"text-violet-700\" \"(css :flex :gap-4 :p-2)\") "'
+        'Styles are expressions. "'
+        '  (code :class "text-violet-700" "(css :flex :gap-4 :p-2)")'
         '      " is not a class name, not an inline style, not a CSS-in-JS template literal. '
         'It is a function call that returns a value. '
         'The value produces a generated class. '