Move 60 performance-related files from webcore/ to web/performance/.
Includes Performance API, PerformanceObserver, Timing, Marks, Measures,
ResourceTiming, ServerTiming, and NetworkLoadMetrics.
Added JSDOMWrapperCache.h include to JSPerformanceEntryCustom.cpp.
Updated cmake/Sources.json and cmake/targets/BuildBun.cmake.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
