refactor(dynamic): replace Spring annotation stubs with real dependencies, integrate MockMvc-based invocation for Spring controllers, and enhance runtime classpath logic

tests/dynamic_fixtures/java/spring_controller/Benign.java

@@ -1,15 +1,22 @@
-// Phase 14 — Spring `@RestController`, benign.
+// Spring `@RestController`, benign.
 //
 // Same shape as the vuln but the controller runs a fixed echo and
 // drops `payload`.
 
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
 @RestController
 @RequestMapping("/run")
 public class Benign {
     @Autowired
     private CommandRunner runner;
 
-    public String run(String payload) throws Exception {
+    @GetMapping
+    public String run(@RequestParam("payload") String payload) throws Exception {
         System.out.print("__NYX_SINK_HIT__\n");
         CommandRunner r = (runner != null) ? runner : new CommandRunner();
         String out = r.run("echo hello");