fix: remove A/E buttons, make automation always expanded, add bottom border

Fixed all three issues:
1. Removed automation (A) and effects (E) toggle buttons from TrackControls
2. Made automation bar always expanded and non-collapsible
3. Added bottom border to effects bar (border-b)

Changes:
- TrackControls.tsx: Removed entire Row 2 (A/E buttons section)
- TrackList.tsx: Removed click handler and chevron from automation header
- TrackList.tsx: Automation lane always visible (no conditional rendering)
- TrackList.tsx: Added border-b to effects bar container
- TrackList.tsx: Added border-b to automation bar for visual consistency

Bars are now permanent, always-visible UI elements at the bottom of tracks.

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

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

components/tracks/TrackControls.tsx

@@ -143,41 +143,6 @@ export function TrackControls({
             M
           </button>
         </div>
-
-        {/* Control Buttons Row 2: A/E */}
-        <div className="flex items-center gap-0.5 w-full justify-center">
-          {/* Automation Toggle */}
-          {onAutomationToggle && (
-            <button
-              onClick={onAutomationToggle}
-              className={cn(
-                'h-5 w-5 rounded-md flex items-center justify-center transition-all text-[9px] font-bold',
-                showAutomation
-                  ? 'bg-primary text-primary-foreground shadow-md shadow-primary/30'
-                  : 'bg-card hover:bg-accent text-muted-foreground border border-border/50'
-              )}
-              title="Toggle automation"
-            >
-              A
-            </button>
-          )}
-
-          {/* Effects Button */}
-          {onEffectsClick && (
-            <button
-              onClick={onEffectsClick}
-              className={cn(
-                'h-5 w-5 rounded-md flex items-center justify-center transition-all text-[9px] font-bold',
-                showEffects
-                  ? 'bg-primary text-primary-foreground shadow-md shadow-primary/30'
-                  : 'bg-card hover:bg-accent text-muted-foreground border border-border/50'
-              )}
-              title={showEffects ? 'Hide effects' : 'Show effects'}
-            >
-              E
-            </button>
-          )}
-        </div>
       </div>
     </div>
   );