Adds the addAccountByToken procedure to accountProcedures(), which accepts an email and raw OAuth token, stores the token as claudeAiOauth credentials, and upserts the account (create or updateAccountAuth based on findByEmail). Covers the four scenarios with unit tests: new account, existing account, empty email, and empty token validation errors. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>