Clean up all references to authenticatedData

- De facto, was being assumed everywhere if authenticatedData is null, that it's not logged in. This isn't true because the data can still be loading. Update the hook to send additional states.
- Bonus: Delete model picker code and a slew of unused imports.

src/interface/web/app/components/chatInputArea/chatInputArea.tsx

@@ -409,7 +409,6 @@ export const ChatInputArea = forwardRef<HTMLTextAreaElement, ChatInputProps>((pr
                 <LoginPrompt
                     onOpenChange={setShowLoginPrompt}
                     isMobileWidth={props.isMobileWidth}
-                    loginRedirectMessage={loginRedirectMessage}
                 />
             )}
             {uploading && (