Add credential extraction, injection, and UI for managing Claude and Codex OAuth credentials in sandbox environments. Credentials are stored per-user in the user actor, injected on task owner swap, and periodically re-extracted to capture token refreshes. Frontend account settings show provider sign-in status.
Changes:
- User actor: new userProviderCredentials table with upsert/get actions
- Task workspace: extract/inject provider credentials, integrate with owner swap and polling
- App snapshot: include provider credential status (anthropic/openai booleans)
- Frontend: new Providers section in account settings
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
