Fix UI bugs (#8)

* Auto create conversation when the user starts

* Add conversation rename rule check

* Fix empty name during save

* Confirm deleting conversation

* Show warning if users don't select file when upload files in the File Index

* Feedback when user uploads duplicated file

* Limit the file types

* Fix valid username

* Allow login when username with leading and trailing whitespaces

* Improve the user

* Disable admin panel for non-admnin user

* Refresh user lists after creating/deleting users

* Auto logging in

* Clear admin information upon signing out

* Fix unable to receive uploaded filename that include special characters, like !@#$%^&*().pdf

* Set upload validation for FileIndex

* Improve user management UI/UIX

* Show extraction error when indexing file

* Return selected user -1 when signing out

* Fix default supported file types in file index

* Validate changing password

* Allow the selector to contain mulitple gradio components

* A more tolerable placeholder screen

* Allow chat suggestion box

* Increase concurrency limit

* Make adobe loader optional

* Use BaseReasoning

---------

Co-authored-by: trducng <trungduc1992@gmail.com>

libs/ktem/ktem/app.py

@@ -229,7 +229,9 @@ class BasePage:
     def _on_app_created(self):
         """Called when the app is created"""
 
-    def as_gradio_component(self) -> Optional[gr.components.Component]:
+    def as_gradio_component(
+        self,
+    ) -> Optional[gr.components.Component | list[gr.components.Component]]:
         """Return the gradio components responsible for events
 
         Note: in ideal scenario, this method shouldn't be necessary.