## Fixes
Closes #28174 
Closes  #30393
Closes #36610
Closes #38616

Updates #31819
Updates #21136

## Context

There was an issue where CJK input could not be entered correctly when
certain keys used during IME composition conflicted with custom
keybindings while the CJK IME was enabled.

(In particular, in Vim mode, the `jj` keybinding in INSERT MODE could
not be entered correctly.)

This issue had already been fixed on Windows, but not on macOS (and
judging from the code, it is likely also present on Linux, although this
has not been verified).

In this change, we aligned the behavior with Windows.

Currently, on Windows, when the CJK ( or other ) IME is enabled, IME
input is prioritized.
Following this behavior, we updated macOS to also prioritize IME input.

| Input source | Source type | ASCII-capable | Result | Behavior |
|---|---|---|---|---|
| Japanese Hiragana | `KeyboardInputMode` | `false` | `true` | IME
handles key first |
| Japanese Romaji | `KeyboardInputMode` | `true` | `false` | Keybinding
matching first |
| Korean | `KeyboardInputMode` | `false` | `true` | IME handles key
first |
| Chinese Pinyin | `KeyboardInputMode` | `false` | `true` | IME handles
key first |
| Armenian | `KeyboardLayout` | `false` | `false` | Keybinding matching
first |
| Ukrainian | `KeyboardLayout` | `false` | `false` | Keybinding matching
first |
| English (ABC) | `KeyboardLayout` | `true` | `false` | Keybinding
matching first |


(Since similar approaches are used in tools like Vim and Neovim, we
consider this policy to be appropriate.)



## Videos
### before fix

https://github.com/user-attachments/assets/9b204220-d0de-4819-8dc4-00ba85169ef6

### after fix


https://github.com/user-attachments/assets/045cc808-8d29-42d2-9de5-f903fcb602db


## How to Review

This change modifies the gpui layer rather than Zed itself, so please
verify the behavior at the gpui level, not just within Zed.

## Self-Review Checklist

<!-- Check before requesting review: -->
- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Release Notes:

- Fixed IME composition on macOS in Vim insert mode with multi-stroke keybindings like `jj`