Missing critical files (install.py, manager.py, update.py) after git clone / ZIP download on Windows portable

Body:

Problem Description
I am encountering a persistent and unusual issue where key files for ComfyUI-Manager (specifically install.py, manager.py, and update.py) are consistently missing from the custom_nodes/ComfyUI-Manager directory after a successful git clone or manual ZIP download/extraction. This prevents the Manager from loading or installing correctly.

Environment
ComfyUI Version: Portable Windows build (downloaded from ComfyUI GitHub Releases, e.g., ComfyUI_windows_portable_nvidia.7z). My base ComfyUI installation is fully functional and launches without errors.
Operating System: Windows 10.
Antivirus: Only Windows Defender is active (no third-party antivirus interfering).
Steps Taken / To Reproduce
Ensured clean ComfyUI portable installation: Performed a complete removal of the previous ComfyUI installation and extracted a fresh ComfyUI_windows_portable_nvidia.7z to C:\Users\YourUserName\Desktop\ComfyUI_windows_portable. This base installation works perfectly.
Attempted ComfyUI Manager installation via git clone:
Opened a terminal in C:\Users\YourUserName\Desktop\ComfyUI_windows_portable\ComfyUI.
Executed: git clone https://github.com/ltdrdata/ComfyUI-Manager.git custom_nodes/ComfyUI-Manager
Result: The git clone command consistently reported 100% success (e.g., "Receiving objects: 100% (21896/21896), 45.27 MiB | 4.64 MiB/s, done. Resolving deltas: 100% (16153/16153), done.").
Attempted ComfyUI Manager installation via manual ZIP download:
Downloaded ComfyUI-Manager-main.zip from the < > Code button on https://github.com/ltdrdata/ComfyUI-Manager.
Extracted the ZIP to a temporary location, then moved and renamed the contained ComfyUI-Manager-main folder to custom_nodes/ComfyUI-Manager.
Verification of files:
Immediately after both git clone and ZIP extraction attempts, I checked the contents of C:\Users\YourUserName\Desktop\ComfyUI_windows_portable\ComfyUI\custom_nodes\ComfyUI-Manager.
Expected Behavior
I expected to find install.py, manager.py, and update.py directly in the custom_nodes/ComfyUI-Manager folder, allowing the Manager to load in ComfyUI or its installation script to run.

Observed Behavior (The Anomaly)
The critical files install.py, manager.py, and update.py are missing from the custom_nodes/ComfyUI-Manager directory.
Instead, only sub-modules like _util.py, _server.py, _downloader.py, _core.py are present, along with various subfolders (e.g., assets, extension, node_db).
Attempting to run the installation script (python custom_nodes/ComfyUI-Manager/install.py) results in a [Errno 2] No such file or directory error, as install.py is not found.
Consequently, the "Manager" button does not appear in the ComfyUI interface.
This behavior is highly unusual, as git clone reports complete success but key files essential for the Manager's operation are consistently absent.

Start by reproducing the Windows portable installation steps with git clone and ZIP extraction into custom_nodes/ComfyUI-Manager, then inspect whether install.py, manager.py, and update.py are present alongside _util.py, _server.py, _downloader.py, and _core.py. Run python custom_nodes/ComfyUI-Manager/install.py and check whether the Manager button appears; done means the expected files are available and the Manager loads.

Written by the indexing model from the issue text.