Remove xvfb-run dependency from rendering process

- Eliminated the use of xvfb-run for headless rendering in the RenderProcessor, simplifying the command execution for Blender.
- Updated the CheckRequiredTools function to remove the check for xvfb-run, reflecting the change in rendering requirements.

internal/runner/runner.go

@@ -68,10 +68,6 @@ func (r *Runner) CheckRequiredTools() error {
 	}
 	log.Printf("Found zstd for compressed blend file support")
 
-	if err := exec.Command("xvfb-run", "--help").Run(); err != nil {
-		return fmt.Errorf("xvfb-run not found - required for headless Blender rendering. Install with: apt install xvfb")
-	}
-	log.Printf("Found xvfb-run for headless rendering without -b option")
 	return nil
 }