feat: implement live audio waveform, frosted contact posters, gestures, and glassmorphism

- Add 32-bar multi-harmonic liquid glass LiveAudioWaveform responding to active, mute, hold, and record states
- Add full-screen frosted ContactPosterBackground with LRU cache integration and fallback monogram
- Add CallGestureManager for Flip to Silence and Proximity Wave to Silence (user toggleable, default off)
- Add 4 acoustic and haptic dialpad profiles (Titanium Glass, Mechanical Relay, Stealth, Classic)
- Add QuickDeclineSheet with 1-tap quick SMS presets and custom reply input
- Add InternationalCountryHelper and DialpadTimezonePill with country flag, local time, and late-night warnings
- Modernize IncomingCallScreen and InCallScreen with tactile glass controls, expanding ring auras, and specular borders
- Add CHANGELOG.md and update README.md and ARCHITECTURE.md