v0.5.30 - Fix stale NOTEBOOKLM_COOKIES auth loop

What's Fixed

Auth loop when NOTEBOOKLM_COOKIES env var is stale (#170)

If you had NOTEBOOKLM_COOKIES set in your MCP config (e.g. claude_desktop_config.json) and those cookies expired, you'd get stuck in an auth loop with no useful error. refresh_auth would return false "success" while silently reloading the same stale cookies. Nothing you did — nlm login, save_auth_tokens, editing auth.json — would fix it.

Now:

• refresh_auth detects the env var and returns a clear, actionable error explaining exactly what to do
• Auth failure messages mention NOTEBOOKLM_COOKIES when it's the likely culprit

Deprecated env vars cleaned up

NOTEBOOKLM_CSRF_TOKEN and NOTEBOOKLM_SESSION_ID are no longer read from the environment. Both are auto-extracted on every client init. Stale values from env were bypassing auto-refresh and causing auth failures.

Troubleshooting docs

Added a new section to AUTHENTICATION.md covering the env var auth trap, how to diagnose it, and both fix options.

Thanks to @nobolso for the thorough root cause analysis that made this fix fast to land!