Completes the account settings surface with the global Accounts list under the
Claude category: each registered account shows a sign-in dot, name, and config
dir, with re-login and remove affordances plus an inline add-account field.
- Sign-in status: accountIsSignedIn, a read-only probe (a .credentials.json, or
an oauthAccount marker in .claude.json; under-reports on macOS keychain).
- Add: registers ~/.claude-<name> and publishes a login action (T-485 opens the
pane).
- Remove: registry-remove, guarded while a workspace is bound — matching the CLI
`account remove`. --purge dir deletion stays on the CLI flag.
All management routes through the AccountRegistry + accountActionChannel, and
the list rebuilds live off the settings notifier. en/nl strings + widget/probe
tests added. Closes T-482.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>