make userid case insensitive

Author: Yuriy Bezsonov

samples/spring-ai-te-agent/ai-agent/src/main/java/com/example/ai/agent/controller/ChatController.java

@@ -56,10 +56,10 @@ public String summarize(@RequestBody(required = false) SummarizeRequest request,
     private String getUserId(String requestUserId, Principal principal) {
         // Production: use authenticated user from Spring Security
         if (principal != null) {
-            return principal.getName();
+            return principal.getName().toLowerCase();
         }
         // Development: use provided userId or default
-        return requestUserId != null ? requestUserId : "user1";
+        return requestUserId != null ? requestUserId.toLowerCase() : "user1";
     }
 
     private boolean hasFile(ChatRequest request) {

samples/spring-ai-te-agent/ai-agent/src/main/java/com/example/ai/agent/service/ChatMemoryService.java

@@ -143,7 +143,7 @@ public MessageWindowChatMemory getPreferencesMemory() {
     }
 
     public void setCurrentUserId(String userId) {
-        this.currentUserId.set(userId);
+        this.currentUserId.set(userId.toLowerCase());
     }
 
     public String getCurrentConversationId() {