feat(macos): implement Unicode text input

[boomyao]

Description

Implement the platf::unicode() function for macOS, which was previously a stub that only logged "Unicode input not yet implemented for MacOS".

The implementation converts incoming UTF-8 text to UTF-16 via CFString, then injects each character as a CGEvent keyboard event using CGEventKeyboardSetUnicodeString(). Surrogate pairs are handled correctly for characters outside the Basic Multilingual Plane (e.g., emoji).

This enables Moonlight clients to send composed text (e.g., CJK characters from mobile IME) directly to the macOS host, matching the existing functionality on Windows (SendInput + KEYEVENTF_UNICODE) and Linux (Ctrl+Shift+U + hex code).

Context: When using Moonlight on Android/iOS with a Chinese/Japanese/Korean input method, the IME completes text composition locally and sends the final text via LiSendUtf8TextEvent(). On Windows and Linux hosts, this text is correctly injected into the active application. On macOS, it was silently dropped because platf::unicode() was unimplemented.

Screenshot

Issues Fixed or Closed

Roadmap Issues

Type of Change

• feat: New feature (non-breaking change which adds functionality)
• fix: Bug fix (non-breaking change which fixes an issue)
• docs: Documentation only changes
• style: Changes that do not affect the meaning of the code (white-space, formatting, missing semicolons, etc.)
• refactor: Code change that neither fixes a bug nor adds a feature
• perf: Code change that improves performance
• test: Adding missing tests or correcting existing tests
• build: Changes that affect the build system or external dependencies
• ci: Changes to CI configuration files and scripts
• chore: Other changes that don't modify src or test files
• revert: Reverts a previous commit
• BREAKING CHANGE: Introduces a breaking change (can be combined with any type above)

Checklist

• Code follows the style guidelines of this project
• Code has been self-reviewed
• Code has been commented, particularly in hard-to-understand areas
• Code docstring/documentation-blocks for new or existing methods/components have been added or updated
• Unit tests have been added or updated for any new or modified functionality

AI Usage

• None: No AI tools were used in creating this PR
• Light: AI provided minor assistance (formatting, simple suggestions)
• Moderate: AI helped with code generation or debugging specific parts
• Heavy: AI generated most or all of the code changes

[ReenigneArcher]

There are clang format issues in this PR. Don't worry, it's easy to fix.

1. Create and activate a python venv in your workspace (optional) - https://docs.python.org/3/library/venv.html#creating-virtual-environments

2. Install dependencies with the following command:

   python -m pip install ".[lint]"

3. Run the following command to fix lint issues:

   python scripts\update_clang_format.py

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Bundle Report

Bundle size has no change ✅

[codecov]

Codecov Report

❌ Patch coverage is 0% with 25 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (master@5ffa66e). Learn more about missing BASE report.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/platform/macos/input.cpp	0.00%	25 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #4980   +/-   ##
=========================================
  Coverage          ?   17.99%           
=========================================
  Files             ?      109           
  Lines             ?    23524           
  Branches          ?    10388           
=========================================
  Hits              ?     4232           
  Misses            ?    14988           
  Partials          ?     4304           

Flag	Coverage Δ
Archlinux	11.59% <ø> (?)
FreeBSD-14.3-amd64	13.58% <ø> (?)
Homebrew-ubuntu-22.04	13.97% <ø> (?)
Linux-AppImage	12.26% <ø> (?)
Windows-AMD64	14.89% <ø> (?)
Windows-ARM64	13.23% <ø> (?)
macOS-arm64	18.99% <0.00%> (?)
macOS-x86_64	18.33% <0.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/platform/macos/input.cpp	34.68% <0.00%> (ø)

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