Better for setup-langtechdepot.ps1 to skip asking for a token after installation

It seems a pity that, after we have run setup-langtechdepot.ps1 and installed the software, if we want to run it again to select another folder to subscribe to, we have to go and find wherever we saved the token, copy it and paste it again.

Here's the display:

Using Syncthing at C:\Users\JimHe\Downloads\LangTechDepot_from_HTML_interface\langtechdepot-windows\syncthing.exe
Waiting for Syncthing...

This machine's device ID: KS24TN4-G2N4SNH-KLOL5TE-SMKOYS6-W4JNXZI-FX3ZYTH-IA6INVK-72DJYAP
No token yet? Register at https://depot.langtech.cloud

Paste your LangTechDepot token:

Can the program tell that this computer has registered with the token already?
If so, let's change it, so that if it knows the device has registered, it doesn't ask for the token.

Or should we continue to distribute langtechdepot-subscribe.ps1, so people can subscribe to other folders without having to locate the token again?

Start by reading setup-langtechdepot.ps1 and langtechdepot-subscribe.ps1 to understand how registration and folder subscription currently work. Check whether the existing scripts expose a persisted registration state or token before deciding between updating setup-langtechdepot.ps1 and continuing to distribute the subscription script. Done means rerunning setup after registration no longer requires locating and pasting the token when selecting another folder.