Fix zombie upscaler processes by killing child processes and upscaler binaries in stop.py

stop.py

@@ -56,6 +56,18 @@ def stop() -> None:
 
     print(f"🛑 Stopping server (PID {pid}) …")
 
+    # Clean up child processes of the server and any lingering upscaler binaries
+    import subprocess
+    try:
+        subprocess.run(["pkill", "-P", str(pid)], capture_output=True)
+    except Exception:
+        pass
+    try:
+        subprocess.run(["pkill", "-f", "realesrgan-ncnn-vulkan"], capture_output=True)
+        subprocess.run(["pkill", "-f", "rife-ncnn-vulkan"], capture_output=True)
+    except Exception:
+        pass
+
     # Graceful shutdown (SIGTERM)
     os.kill(pid, signal.SIGTERM)