feat: Add hybrid mode for compact content in expanded state

[dima6312]

Summary

This PR introduces hybrid mode - a layout option that displays compact leading/trailing content alongside the expanded notch panel. This enables use cases like dictation UIs with persistent waveform indicators, or media players with always-visible controls.

Key additions:

• showCompactContentInExpandedMode property for hybrid layouts
• Automatic hybrid mode fallback for floating style on non-notch Macs
• Public NSScreen extensions for notch detection (hasNotch, notchSize, notchFrame)
• Public isHovering property for hover-based activation patterns

Motivation

When building interfaces like voice dictation UIs, developers need status indicators (waveforms, cancel buttons) that remain visible while expanded content displays below. Previously, compact content was only visible in .compact state on notch Macs and invisible entirely on non-notch Macs.

This PR solves both:

1. Notch Macs: Enable hybrid mode to show compact indicators alongside expanded content
2. Non-notch Macs: Automatic fallback shows the same indicators in floating panels

Usage

let notch = DynamicNotch(
    compactLeading: { WaveformView() },
    compactTrailing: { CancelButton() },
    expanded: { TranscriptView() },
    style: .notch,
    showCompactContentInExpandedMode: true
)

On non-notch Macs, compact() automatically enables hybrid mode in floating style.

  // Dynamically hide compact views
  dynamicNotch.disableCompactLeading = true  // Hides leading, no gap
  dynamicNotch.disableCompactTrailing = true // Hides trailing, no gap

Changes

Features

• showCompactContentInExpandedMode - compact content visible in expanded state
• compactCenterContent - optional center content for floating hybrid mode
• Public NSScreen extensions for notch detection
• Public isHovering for hover observation
• Public disableCompactLeading and disableCompactTrailing properties for dynamic compact view control

Bug Fixes

• Prevent continuation leak in hide() when closePanelTask is cancelled
• Direct compact↔expanded transitions without intermediate hide step
• Proper task cancellation and weak self captures
• Reset namespace on window deinitialization to prevent stale references
• Fix compact content rendering on window recreation during rapid transitions
• Allow compact content to expand horizontally for text labels
• Fix floating mode layout: disabled compact views no longer reserve space (use conditional rendering instead of opacity)

Code Quality

• Structured concurrency with MainActor.run
• animationDuration constant extracted from DynamicNotchStyle
• Accessibility improvements (.accessibilityHidden() for VoiceOver)
• Comprehensive test coverage (19 tests)
• DocC and README documentation

Test Plan

• All 19 tests pass
• Project builds with zero warnings
• Hybrid mode works on notch Macs
• Floating fallback works on non-notch Macs
• Rapid state transitions render correctly
• Text labels in compact content expand properly

Breaking Changes

None. All APIs are additive with sensible defaults.

Demo

┌─────────────────────────────────────────┐
│  [indicator]    ████████    [cancel]    │  ← Compact content visible
├─────────────────────────────────────────┤
│                                         │
│           Expanded Content              │  ← Expanded content below
│                                         │
└─────────────────────────────────────────┘