fix: standardize meter colors to use 500 shades

- Changed RMS meter colors from 400 to 500 shades (brighter)
- Both Peak and RMS meters now use same color brightness
- Applied to both TrackFader and MasterFader
- Provides better visual consistency between the two meter types

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

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

components/controls/MasterFader.tsx

@@ -118,9 +118,9 @@ export function MasterFader({
           >
             <div className={cn(
               'w-full h-full',
-              rmsDb > -3 ? 'bg-red-400' :
-              rmsDb > -6 ? 'bg-yellow-400' :
-              'bg-green-400'
+              rmsDb > -3 ? 'bg-red-500' :
+              rmsDb > -6 ? 'bg-yellow-500' :
+              'bg-green-500'
             )} />
           </div>
         </div>

components/tracks/TrackFader.tsx

@@ -120,9 +120,9 @@ export function TrackFader({
           >
             <div className={cn(
               'w-full h-full',
-              rmsDb > -3 ? 'bg-red-400' :
-              rmsDb > -6 ? 'bg-yellow-400' :
-              'bg-green-400'
+              rmsDb > -3 ? 'bg-red-500' :
+              rmsDb > -6 ? 'bg-yellow-500' :
+              'bg-green-500'
             )} />
           </div>
         </div>