[Bug] OAuth login expires or aborts with an unhelpful recovery message

[LIghtJUNction]

Problem

Pi login can fail with:

lmm.best
授权 Pi

请求已过期、账号已切换或无权访问。请从 Pi 重新发起登录。

or:

Error: Failed to login to LMM: This operation was aborted

This is especially easy to trigger after OAuth scopes change (for example adding usage:read) or when Pi has a stale/expired local grant. The current message does not tell the user whether the browser authorization expired, the account changed, the callback timed out, or the server rejected the grant.

Expected behavior

• Detect stale credentials before model use and request a clean re-login.
• Treat a missing/expired scope as a recoverable reauthorization, not a generic abort.
• Distinguish user cancellation from callback timeout and server-side authorization rejection.
• Clear or quarantine only the stale provider credential; do not affect other providers.
• Explain that an existing grant may need /logout followed by /login.

Acceptance criteria

• Tests cover expired access tokens, revoked grants, account/session changes, expired browser transactions, and user cancellation.
• The UI displays a stable recovery message rather than only operation was aborted.