fix: ensure canvas renders when dialog opens

Fixed canvas visualization not painting sometimes by:
- Adding `open` prop check before rendering
- Adding `open` to useEffect dependencies
- Adding dimension validation for dynamic canvas sizes
- Ensures canvas properly renders when dialog becomes visible

Affected dialogs: DynamicsParameterDialog, TimeBasedParameterDialog,
AdvancedParameterDialog

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

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

components/effects/AdvancedParameterDialog.tsx

@@ -91,6 +91,8 @@ export function AdvancedParameterDialog({
 
   // Draw visual feedback
   React.useEffect(() => {
+    if (!open) return;
+
     const canvas = canvasRef.current;
     if (!canvas) return;
 
@@ -210,7 +212,7 @@ export function AdvancedParameterDialog({
     ctx.moveTo(0, height / 2);
     ctx.lineTo(width, height / 2);
     ctx.stroke();
-  }, [parameters, effectType]);
+  }, [parameters, effectType, open]);
 
   const handleApply = () => {
     onApply({ ...parameters, type: effectType } as AdvancedParameters);