fix(desktop): ignore IME composition enter

[tgfjt]

What does this PR do?

This fixes Hermes Desktop submitting a chat message when users press Enter to confirm Japanese/Chinese/Korean IME conversion.

The desktop composer currently handles every non-Shift Enter keydown as submit. During IME composition, the conversion-confirmation Enter also reaches the composer as a keydown event, so confirming text can accidentally send the unfinished message.

This PR adds a small IME composition guard before the submit shortcut runs. It checks both nativeEvent.isComposing and the browser IME processing key code 229, which covers the common macOS/Electron path where composition Enter may not be represented as a normal Enter event. Normal Enter submission remains unchanged.

Related Issue

Fixes #37483

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 🔒 Security fix
• 📝 Documentation update
• ✅ Tests (adding or improving test coverage)
• ♻️ Refactor (no behavior change)
• 🎯 New skill (bundled or hub)

Changes Made

• apps/desktop/src/app/chat/composer/index.tsx
  • Skip composer keydown shortcuts while an IME composition event is active, preventing conversion-confirmation Enter from submitting the message.
• apps/desktop/src/app/chat/composer/ime.ts
  • Add isImeCompositionKeyEvent() helper for nativeEvent.isComposing and IME processing keyCode === 229.
• apps/desktop/src/app/chat/composer/ime.test.ts
  • Add regression tests for IME composition Enter, macOS/Electron keyCode === 229, and normal Enter behavior.

How to Test

1. In Hermes Desktop on macOS, focus the chat composer and enable a Japanese IME.
2. Type text that requires conversion, then press Enter to confirm the conversion.
   • Expected: the converted text stays in the composer and is not submitted.
3. Press Enter again after composition has ended.
   • Expected: the message submits normally.

Automated checks run locally:

npm run test:ui -- src/app/chat/composer
npm run type-check
npx eslint src/app/chat/composer/ime.ts src/app/chat/composer/ime.test.ts src/app/chat/composer/index.tsx
npm run build

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits (fix(scope):, feat(scope):, etc.)
• I searched for existing PRs to make sure this isn't a duplicate
• My PR contains only changes related to this fix/feature (no unrelated commits)
• I've run pytest tests/ -q and all tests pass
• I've added tests for my changes (required for bug fixes, strongly encouraged for features)
• I've tested on my platform: macOS 26.2 / Hermes Desktop Electron app

Documentation & Housekeeping

• I've updated relevant documentation (README, docs/, docstrings) — or N/A
• I've updated cli-config.yaml.example if I added/changed config keys — or N/A
• I've updated CONTRIBUTING.md or AGENTS.md if I changed architecture or workflows — or N/A
• I've considered cross-platform impact (Windows, macOS) per the compatibility guide — or N/A
• I've updated tool descriptions/schemas if I changed tool behavior — or N/A

Screenshots / Logs

> hermes@0.15.1 test:ui
> vitest run --environment jsdom src/app/chat/composer

✓ src/app/chat/composer/ime.test.ts (3 tests)
✓ src/app/chat/composer/rich-editor.test.ts (1 test)

Test Files  2 passed (2)
Tests       4 passed (4)

> hermes@0.15.1 type-check
> tsc -b

npx eslint src/app/chat/composer/ime.ts src/app/chat/composer/ime.test.ts src/app/chat/composer/index.tsx
# passed

npm run build
# built successfully

[tgfjt]

dup #37483