Refine notch hover timing and width scaling

[Lucker-QY]

Summary

• Add a prehover phase for the notch hover interaction so quick mouse pass-through reverses the first-stage animation instead of opening the full panel.
• Tune hover timing to expand after 0.5s and collapse 0.5s after mouse leave.
• Change the collapsed width scale slider from 10% steps to 1% steps while keeping the existing 50%...150% range.

Details

The hover behavior now uses a small state machine (collapsed, prehover, expanded) to separate the immediate visual acknowledgement from the delayed full expansion. This makes accidental cursor passes feel lighter while preserving the existing expanded panel behavior.

The collapsed width scale range is centralized in NotchWidthScale, and the settings slider now uses the shared constants so the UI and width calculation stay aligned.

Validation

• swift build -c release passes.
• swift test --filter NotchPanelViewTests could not run in my local environment because this machine only has Command Line Tools selected and SwiftPM fails to import XCTest (no such module 'XCTest').