fix: to_latex MCP tool now returns ##TEXFORM## prefix for KaTeX rendering

app/src/main/java/com/nonvioce/ijs/McpServer.java

@@ -478,8 +478,10 @@ public class McpServer extends NanoHTTPD {
 
     private String callToLatex(String expression) {
         String result = symjaEngine.toTeX(expression);
-        AppSession.publishMcpEvent("TeXForm[" + expression + "]", result);
-        return result;
+        // 添加 ##TEXFORM## 前缀以便控制台识别并 KaTeX 渲染
+        String prefixed = "##TEXFORM##" + result;
+        AppSession.publishMcpEvent("TeXForm[" + expression + "]", prefixed);
+        return prefixed;
     }
 
     private String callListPlugins() {