feat: first chunk of lexer/parser translation.

InkBlot/Visitor/ListenerStory.cs

@@ -10,11 +10,10 @@ public partial class Listener
 
     public override void ExitStory(InkBlotAntlrGrammarParser.StoryContext context)
     {
-        var storyNodes = context.children.Select(child => child switch
-        {
-            InkBlotAntlrGrammarParser.ContentTextContext contentText => new Content(GetContentText(contentText)),
-            _ => throw new InvalidOperationException($"unknown context of type {child.GetType()}")
-        });
+        var storyNodes = context
+            .topLevelStatements()
+            .contentText()
+            .Select(child => new Content(GetContentText(child)));
         _story = new Story(storyNodes);
     }
 }