What does this PR do?

Adds a small tests-only regression suite for mixed Arabic/English bidi rendering in Hermes Ink.

This change does not introduce locale plumbing, translation files, or runtime behavior changes. It only documents and protects the current bidi behavior for a realistic RTL/LTR mixed-text case in the TUI layer.

Related Issue

Refs #12375

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

• Added ui-tui/packages/hermes-ink/src/ink/bidi.test.ts
• Added focused regression coverage for:
  • pure LTR text remaining unchanged
  • Arabic text exercising the RTL path indirectly
  • mixed Arabic/English technical text such as مرحبا gpt-5

How to Test

1. cd ui-tui/packages/hermes-ink
2. npm test -- packages/hermes-ink/src/ink/bidi.test.ts
3. Confirm the new bidi test file passes

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 14.5

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

N/A — tests-only change.