### TL;DR
Refactor space-triggered AI Widget activation logic from `keydown` to `keypress` event listeners
### Background
The `keydown` event triggered by a space may originate from:
1. Normal space insertion
2. Space triggered by input method confirming candidate words
In scenarios like (2), some browsers (see [ISSUE](https://github.com/toeverything/AFFiNE/issues/11541)) and input method callbacks produce events identical to scenario (1),making it impossible to distinguish between the two.
To fix this, the space-activated AI listener uses the `keypress` event:
In scenario 2, `event.which !== 32` (may be `30430` or other values) can be used to differentiate from scenario 1.
> CLOSE BS-3081
