perf(macos): add high-FPS ScreenCaptureKit VideoToolbox path

[bdjben]

Description

Adds a macOS ScreenCaptureKit display capture path and a native VTCompressionSession VideoToolbox encoder path for high-FPS streaming. The encode loop is paced from an independent output clock so streams can continue emitting encoded frames at the requested cadence even when macOS capture delivers fresh frames at a lower rate.

This also preserves the client-requested stream dimensions, includes the cursor in ScreenCaptureKit output, and adds capture/encode/send rate logging useful for diagnosing macOS high-FPS behavior.

Local validation was done on an Apple Silicon Mac mini with a Windows Moonlight client and two simultaneous Sunshine-derived app instances: one stream at 120 FPS and one stream at 60 FPS. The successful run showed approximately 120 FPS and 60 FPS output respectively, with native VideoToolbox reporting failed_packets=0 in the tested windows.

Known follow-up areas: the high-FPS pacing strategy is intentionally aggressive and should be reviewed for CPU efficiency, and broader testing is needed across macOS versions, display configurations, codecs, HDR/SDR modes, and client settings.

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

[sonarqubecloud]

Quality Gate failed

Failed conditions
5 New issues
5 New Code Smells (required ≤ 0)

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