Fix frozen entry and HUD regressions

[yvette-carlisle]

Summary

• warm and retain live/frozen sampling so entering Frozen remains responsive and toolbar handoff is ready
• repair HUD color rolling animation and keep the Live HUD from starting black or flashing through #000000
• harden drag/click smoke coverage and mouse release handling for native visual contract tests
• default Liquid Glass style to Regular and cache macOS 26 Liquid Glass availability with Classic fallback

Verification

• cargo make lint-swift
• git diff --check
• ./scripts/perf/macos.sh
  • local scroll-capture benchmarks: no regression detected
  • native HUD follow: PASS
  • native visual contract: PASS, including two drag freezes and one click guard
  • replay-scroll-capture: SKIP, no local recorded trace under Application Support

Manual authority lane.