style: add custom-scrollbar styling to all dialog scrollable areas

Added custom-scrollbar class to scrollable elements in:
- EffectBrowser dialog content area
- ProjectsDialog projects list
- CommandPalette results list
- Modal content area
- TrackList automation parameter label containers

This ensures consistent scrollbar styling across all dialogs and UI elements.

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

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

components/tracks/TrackList.tsx

@@ -420,7 +420,7 @@ export function TrackList({
                         )}
 
                         {/* Parameter labels - always visible */}
-                        <div className="flex items-center gap-1.5 flex-1 min-w-0 overflow-x-auto">
+                        <div className="flex items-center gap-1.5 flex-1 min-w-0 overflow-x-auto custom-scrollbar">
                           {automatedParams.map((paramName, index) => (
                             <span
                               key={index}
@@ -996,7 +996,7 @@ export function TrackList({
                         )}
 
                         {/* Parameter labels - always visible */}
-                        <div className="flex items-center gap-1.5 flex-1 min-w-0 overflow-x-auto">
+                        <div className="flex items-center gap-1.5 flex-1 min-w-0 overflow-x-auto custom-scrollbar">
                           {automatedParams.map((paramName, index) => (
                             <span
                               key={index}