Enhance: DevUI has bad UX when inputting Japanese

[soundTricker]

[Description of issue]
On DevUI chat input, we can send a message by typing the Enter Key.
When inputting Japanese, we must decide the conversion candidate by pressing the Enter key, but DevUI chat input send the message when decide the conversion candidate.
So we can't send full message when using Japanese.

[How to re-produce the issue]

1. Show DevUI
2. Input Japanese message on chat input.

[Proposal]
Changing the shortcut key to Ctrl(Command) + Enter or adding the send button and disable shortcut key.
Or using isComposing property.
https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/isComposing

[Kavyapriya-1804]

It would be good to have the FrontEnd codebase as requested in google/adk-python#118 for contributions.
cc: @wyf7107

[wyf7107]

Yes, we will keep this in mind, thanks for sharing !

[soundTricker]

Note: i will make a PR for this soon.

[wyf7107]

I think this is fixed, feel free to re-open it. (We will update adk web soon, source code is up to date)

[soundTricker]

@wyf7107 If you means current code 55761aa is fixed this problem, i tried but it is not fixed the problem.
And i don't have a permission for re-open this issue.