fix(desktop): steer from live composer text

[supplefrog]

What does this PR do?

Fixes an intermittent Hermes Desktop composer bug where Ctrl+Enter / Cmd+Enter can miss freshly typed steer text. The shortcut branch now mirrors the existing plain-Enter race fix: it reads the live contentEditable DOM synchronously before deciding whether steering is possible, then syncs draftRef/composer state before calling steerDraft().

Related Issue

Fixes #53659

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
  • Makes the Ctrl/Cmd+Enter steer branch read composerPlainText(editorRef.current) instead of relying on render-derived canSteer.
  • Makes steerDraft() validate steerability from draftRef.current so the freshly synced text is honored in the same keydown event.
• apps/desktop/src/app/chat/composer/enter-submit-dom-race.test.tsx
  • Adds a regression case proving fast-typed text is steered on Ctrl+Enter even before composer state has synced.

How to Test

1. Start a Desktop chat turn that is still running.
2. Type a steering message and immediately press Ctrl+Enter / Cmd+Enter.
3. The freshly typed text should steer the active run instead of being swallowed.

Local verification:

• npm --prefix apps/desktop run typecheck — passed
• npm --prefix apps/desktop run test:ui -- src/app/chat/composer/enter-submit-dom-race.test.tsx src/app/chat/composer/composer-text-guard.test.tsx — 2 files, 8 tests passed
• npm --prefix apps/desktop run build — passed
• git diff --check — passed

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: Windows 10

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

No screenshot; this is a keyboard timing fix. The regression is covered by the added jsdom DOM-keydown test.

[supplefrog]

Closing this duplicate in favor of #53668, which fixes the same issue (#53659) with broader focused coverage and already has CI signal.