Alternative.disabled: announced but not yet takeable

The button renders disabled (title 'Not yet') and submit_answer
refuses the alternative server-side - lysbue's disabled flag, back as
content, for advertising a path before it works.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

style/main.css

@@ -675,6 +675,13 @@ textarea:focus {
   cursor: wait;
 }
 
+/* A content-disabled alternative (`disabled: true`): announced, not
+   yet takeable - reads as a promise, not as a stuck form. */
+.alt-submit.soon:disabled {
+  cursor: not-allowed;
+  opacity: 0.6;
+}
+
 .gate-card {
   text-align: center;
 }