[Feature] harden persisted session token

A clear and concise description of the feature you'd like to see

the token comes from discord and is persisted in chromium profile. malware can read it easily. at least, make it os-backed encryption.

Implementation Notes

maybe use electron safeStorage api? my threat modeling scope

• malware scans chromium & electron profile
• malware copies vesktop profile

Additional context

i saw a previous closed #1250

Request Agreement

• I've searched existing issues and this hasn't been suggested before
• This is a core modification feature, not a plugin request (those go in Discord)
• This feature would benefit most users, not just a specific use case
• I am willing to work on this myself