Added a keep-alive function to the AuthController

src/main/java/com/psg/dlsysinfo/dl_sysinfo_server/controller/AuthController.java

@@ -162,6 +162,31 @@ public class AuthController {
             return ResponseEntity.status(HttpStatus.BAD_REQUEST).body("Incorrect current password");
         }
     }
+    @PostMapping("/refresh")
+  public ResponseEntity<?> refreshToken(HttpServletRequest request, HttpServletResponse response) {
+      String token = tokenResolver.resolveToken(request);
+
+      if (token != null && jwtUtil.validateToken(token)) {
+          String username = jwtUtil.extractUsername(token);
+          // Generate new token with extended expiry
+          String newToken = jwtUtil.generateToken(...); // same params as login
+
+          // Set new cookie
+          ResponseCookie cookie = ResponseCookie.from("authToken", newToken)
+              .httpOnly(true)
+              .secure(true)
+              .path("/")
+              .sameSite("None")
+              .maxAge(60 * 60)
+              .domain(resolveCookieDomain(request))
+              .build();
+
+          response.addHeader(HttpHeaders.SET_COOKIE, cookie.toString());
+          return ResponseEntity.ok(Map.of("message", "Token refreshed"));
+      }
+
+      return ResponseEntity.status(401).body(Map.of("error", "Invalid token"));
+  }
 
 
 }