fix(server): a hub credential replaced with another provider gets its own reading

The usage reading key includes the account's provider, so a Claude login
replaced by Codex under the same file id and email isn't shown the old
reading and driver.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
122af9bef1Yannic Charlon committed on 10/17/2026, 10:48:24 PMparent7d6cc5b
2 files changedLine totals unavailable