Fix desktop UX and configuration

Changes:
- MainLayoutController: Analytics access restricted to ADMIN only
  - STAFF users default to Sales view instead of Analytics
  - Logo click redirects STAFF to Sales, ADMIN to Analytics
  - Analytics button hidden for STAFF users
- LoginController: Added CUSTOMER login rejection with clear message
  - CUSTOMER role users are now rejected at login with helpful error
  - Directs customers to use web/mobile applications instead
- Configuration cleanup: Removed connectionpetstore.properties from project root
  - Config file remains in src/main/resources for proper packaging
  - ApiConfig already loads from classpath correctly

These changes ensure proper role-based access control and clean configuration management.

src/main/java/org/example/petshopdesktop/controllers/LoginController.java

@@ -63,6 +63,13 @@ public class LoginController {
             if (token == null || roleStr == null) {
                 throw new IllegalStateException("Token or role is null");
             }
+
+            if ("CUSTOMER".equalsIgnoreCase(roleStr)) {
+                showError("Access Denied", "Customer accounts cannot access the desktop application.\n\nPlease use the web or mobile application instead.");
+                txtPassword.clear();
+                return;
+            }
+
             Role role = Role.valueOf(roleStr.toUpperCase());
 
             UserSession.getInstance().login(null, username, role, token);

src/main/java/org/example/petshopdesktop/controllers/MainLayoutController.java

@@ -173,8 +173,14 @@ public class MainLayoutController {
 
     @FXML
     void logoClicked(MouseEvent event) {
-        loadView("analytics-view.fxml");
-        updateButtons(btnAnalytics);
+        UserSession session = UserSession.getInstance();
+        if (session.isAdmin()) {
+            loadView("analytics-view.fxml");
+            updateButtons(btnAnalytics);
+        } else {
+            loadView("sale-view.fxml");
+            updateButtons(btnSalesHistory);
+        }
     }
 
     @FXML
@@ -201,8 +207,14 @@ public class MainLayoutController {
     public void initialize() {
         applyRBAC();
 
-        loadView("analytics-view.fxml");
-        updateButtons(btnAnalytics);
+        UserSession session = UserSession.getInstance();
+        if (session.isAdmin()) {
+            loadView("analytics-view.fxml");
+            updateButtons(btnAnalytics);
+        } else {
+            loadView("sale-view.fxml");
+            updateButtons(btnSalesHistory);
+        }
     }
 
     private void applyRBAC() {
@@ -241,6 +253,11 @@ public class MainLayoutController {
             separatorAdmin.setManaged(isAdmin);
         }
 
+        if (btnAnalytics != null) {
+            btnAnalytics.setVisible(isAdmin);
+            btnAnalytics.setManaged(isAdmin);
+        }
+
         btnSalesHistory.setText(isAdmin ? "Sales History" : "Sales");