"Neither python -m pip nor uv are available" error comes on starting ComfyUI with ComfyUI-Manager

**OS:** Nobara Linux 42 KDE
**ComfyUI:** v0.3.64
**ComfyUI-Manager:** v3.37

---

I was using ComfyUI and ComfyUI-Manager using Python v3.13 venv until yesterday. Today I deleted that venv folder and created a new one with Python v3.12. Then I reinstalled ComfyUI pip requirements and tried to start the server using the command `python main.py` in the activated venv. But I got this error:

```
venv ❯ python main.py
[START] Security scan
[ComfyUI-Manager] Neither python -m pip nor uv are available. Cannot proceed with package operations.
Failed to execute startup-script: /home/username/Applications/ComfyUI/custom_nodes/comfyui-manager/prestartup_script.py / Neither pip nor uv are available for package management
```

`pip` is installed and listed as a module when I check `pip list`.

See the output of this command:
```
venv ❯ python -c "import subprocess; print(subprocess.run(['python', '-m', 'pip', '--version'], capture_output=True, text=True))"
CompletedProcess(args=['python', '-m', 'pip', '--version'], returncode=0, stdout='pip 25.2 from /home/username/Applications/ComfyUI/venv/lib64/python3.12/site-packages/pip (python 3.12)\n', stderr='')
```

Doesn't this mean that `pip` is properly installed? Then why is that error showing up?