Fix live loupe sampling and chrome stacking

[yvette-carlisle]

Summary

• keep live loupe visible by reusing the latest compatible loupe patch while fresh RGB sampling catches up
• keep HUD/loupe glass and chrome above selection flow without reintroducing dynamic flow masking
• move scrim hole geometry to a shared even-odd path so HUD/loupe glass can keep punchouts without clear-blend residue

Verification

• cargo make fmt-swift-check
• cargo make build-swift-strict
• cargo make test-macos-native-host
• HUD_FOLLOW_CASES=loupe PATH_DURATION_MS=1800 PATH_CYCLES=2 scripts/smoke/native-hud-follow-macos.sh
• VISUAL_CONTRACT_CASES=liquid REPEATED_DRAG_FREEZES=1 REPEATED_CLICK_FREEZES=0 scripts/smoke/native-visual-contract-macos.sh
• git diff --check