[BUG] Device-code authentication for Kusto does not persist between runs

[tanmoyio]

Running any PyGraphistry code path that authenticates to Kusto with device-code auth always triggers a new To sign in, open https://microsoft.com/devicelogin and enter the code … prompt. The access/refresh tokens are not written to cache, so the session is never reused.

Expected behavior
Access + refresh tokens should be cached (file or keychain, depending on platform / env vars).
Re-running within token lifetime (≈ 1 h access / 24 h refresh) should use the cached credentials and run silently.