Assemble voice-to-text screen layout

[fbraza]

Summary

Assemble the overall voice-to-text screen scaffold using the new widgets.

Requirements

• Create VoiceToTextScreen with a Scaffold background of Color(0xFFE8E8E0) and wrap content in a SafeArea.
• Arrange content in a Column with Expanded children matching the guide (transcription flex=2, waveform flex=3).
• Insert the TextDisplayWidget, WaveformWidget, TimerWidget, and ControlButtonsRow in the proper order with approximately 16-20px vertical spacing.
• Attach the BottomNavigationBar implementation to the scaffold.
• Ensure layout adapts to various screen sizes and orientations without overflow.

Acceptance Criteria

• Screen renders all components in the specified order with appropriate spacing.
• Resizing or rotating the emulator preserves layout integrity.
• Bottom navigation remains anchored while the main content scrolls as necessary.
• Screen integrates with the provider setup for dynamic state updates.