Add support for Google Keep API with domain-wide delegation for
Google Workspace accounts.
New commands:
- `gog keep list` - list all notes
- `gog keep get <noteId>` - get a specific note
- `gog auth keep <email> --key <path>` - configure service account
The Keep API requires Workspace with domain-wide delegation because
Google restricts the Keep scope to enterprise use. Once configured,
the service account is auto-detected for the specified email.
Features:
- Service account authentication with impersonation
- Auto-detection of stored service account credentials
- JSON output support for scripting
- Manual override with --service-account and --impersonate flags
