Add endpoint to retrieve current user name (#1018)

Introduces a new GET /name endpoint in UserService that returns the current user's name from the environment context.

Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: vinokurig

wsmaster/che-core-api-user/src/main/java/org/eclipse/che/api/user/server/UserService.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012-2025 Red Hat, Inc.
+ * Copyright (c) 2012-2026 Red Hat, Inc.
  * This program and the accompanying materials are made
  * available under the terms of the Eclipse Public License 2.0
  * which is available at https://www.eclipse.org/legal/epl-2.0/
@@ -51,6 +51,20 @@ public String getId() {
     return userId();
   }
 
+  @GET
+  @Path("/name")
+  @Produces(TEXT_PLAIN)
+  @Operation(
+      summary = "Get current user name",
+      responses = {
+        @ApiResponse(
+            responseCode = "200",
+            description = "The response contains current user's name"),
+      })
+  public String getUser() {
+    return EnvironmentContext.getCurrent().getSubject().getUserName();
+  }
+
   private static String userId() {
     return EnvironmentContext.getCurrent().getSubject().getUserId();
   }