lite login used to write the minted cli-session key in cleartext to
~/.litellm/token.json. The secret material (key plus any JWT) now goes
to the OS keychain through the optional keyring package, with the 0600
file kept for non-secret metadata and as the fallback on headless boxes.
Legacy plaintext files keep authenticating and are migrated into the
keychain, then scrubbed, on first read. A secret still on disk always
outranks the keychain entry, so a failed keychain write can never
resurrect a stale key. LITELLM_PROXY_API_KEY and --api-key precedence
is unchanged, lite logout clears both stores and warns when the
keychain will not release the entry, and ~/.litellm is created 0700
(tightened from 0755 where an older CLI left it broader).
LITELLM_CLI_DISABLE_KEYRING=1 forces the file fallback.
