fix: wrap reply message content in markdown code block in web template

The replyMessage function now encloses the quoted message in triple backticks with a markdown language specifier, ensuring proper rendering of the quoted content in the chat input field.

src/snek/templates/web.html

@@ -136,7 +136,7 @@ chatInputField.textarea.focus();
 
 // --- Reply helper ---
 function replyMessage(message) {
-    chatInputField.value = "markdown\n> " + (message || '') + "\n";
+    chatInputField.value = "```markdown\n> " + (message || '') + "\n```\n";
     chatInputField.focus();
 }