Add executing tests for MacOSOptimizationManager (L5 macOS)

[schatt]

Summary

MacOSOptimizationManager and MacOSPerformanceStrategy in Framework/Sources/Platform/macOS/Views/Extensions/PlatformMacOSOptimizationsLayer5.swift have no executing tests. Spawned from #402: the orphan LayeredTestingSuite L5 file was removed rather than wired; its manager tests never ran and would have locked placeholder constants (strategy == .standard, isMacOSOptimized == false) without proving anything on a green lane.

Current production (macOS-only)

• MacOSPerformanceStrategy: String, CaseIterable (standard, optimized, highPerformance, maximumPerformance).
• MacOSOptimizationManager.shared (@MainActor).
• getCurrentPerformanceStrategy() — internal, always returns .standard (comment: placeholder).
• applyMacOSOptimizations() — internal no-op.
• isMacOSOptimized — public, always false (TODO).
• macOSVersion — public, ProcessInfo.processInfo.operatingSystemVersionString.

Desired tests

Add tests in SixLayerFrameworkUnitTests (macOS unit lane; wrap in #if os(macOS)). Strict TDD (strict-tdd-definition): invert new observations, runtime red, then green. No .serialized.

Lock observable current contracts, not the TODOs as if they were implemented:

• MacOSPerformanceStrategy.allCases is complete and raw values are non-empty / unique.
• shared is a stable singleton (===).
• macOSVersion is non-empty and matches ProcessInfo on the test host.
• If testing the internal placeholders via @testable: document that .standard / false are current stub behavior, so a real implementation is a deliberate test change — or skip those until the API is designed.

Do not host views. Do not reintroduce LayeredTestingSuite.

Out of scope

• Implementing the TODO optimizations (window/menu/a11y). That is a product issue, not this test gap.
• iOS L5 haptic coverage — separate issue.

References

• Parent: Wire or remove orphan LayeredTestingSuite (not in any XcodeGen target) #402 (remove orphan LayeredTestingSuite)
• File: PlatformMacOSOptimizationsLayer5.swift

[schatt]

Sibling: #423 (platformIOSHapticFeedback).

[schatt]

100% coverage cluster: #423 #424 #425; tracker #426.