fix: always show level meter and increase track height to 180px

Fixed layout issues with the level meter:

Track Height:
- Increased DEFAULT_TRACK_HEIGHT from 150px to 180px
- Ensures enough vertical space for all controls without clipping

Level Meter Display:
- Now always visible (not conditional on recording state)
- Shows "Input" with mic icon when track is armed or recording
- Shows "Level" with volume icon when not recording
- Displays appropriate level based on state

This prevents the meter from being cut off and provides consistent
visual feedback for all tracks. Future enhancement: show actual
playback output levels when not recording.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

types/track.ts

@@ -59,6 +59,6 @@ export const TRACK_COLORS: Record<TrackColor, string> = {
   gray: 'rgb(156, 163, 175)',
 };
 
-export const DEFAULT_TRACK_HEIGHT = 150;
+export const DEFAULT_TRACK_HEIGHT = 180;
 export const MIN_TRACK_HEIGHT = 60;
 export const MAX_TRACK_HEIGHT = 300;