feat(three-stage-scan): add split-sink fixtures the regex scan misses

benchmarks/fixtures/split-sink-java/src/main/java/example/SplitSinkServlet.java

@@ -0,0 +1,12 @@
+package example;
+
+import jakarta.servlet.http.HttpServletRequest;
+import java.sql.Connection;
+
+class SplitSinkServlet {
+  void search(HttpServletRequest request, Connection connection) throws Exception {
+    String term = request.getParameter("q");
+    String sql = String.format("select * from items where title like '%%%s%%'", term);
+    connection.createStatement().executeQuery(sql); // CWE-89 split-sink: sql built on prior line (regex blind spot)
+  }
+}