The CLI half of the multi-account feature (epic T-476; D-6 parity). A new
`claude.account` dispatcher command multiplexes the six sub-verbs over an
injected, Flutter-free AccountStore port (runs under `dart test`):
- add <name> [--dir] register (default ~/.claude-<name>); idempotent, clear
conflict error
- list {accounts, boundAccount (this workspace), detected}
- set <name> bind this workspace (persists)
- unset clear this workspace's binding
- remove <name> [--purge] registry-remove; refuses while any workspace is
bound
- login <name> (publishes the login action)
Registry reads/writes go through the user-scope SettingsStore; side-effects
that only the UI layer can do — respawn on set/unset, the `claude login`
terminal pane, and the --purge rm — are published on accountActionChannel for
the Claude extension to consume (that consumer is T-480 part 2). main.dart
adapts the real AccountRegistry to the port and registers the command alongside
image.show / status.
Adds SettingsStore.keysAt (binding enumeration) and AccountRegistry.boundName /
boundAccountNames. No changelog yet — set/unset don't auto-respawn until part 2,
so the feature isn't user-complete. Verb behaviour + payloads + the in-use
guard are unit-tested against a fake store.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>