A service's slug derives from its class name

[czpython]

Service.name is now Service.slug, and nobody declares it: the slug derives from the class name (Gmail → gmail, GoogleCalendar → google_calendar), and the card heading derives from the slug. A minimal service is a class name and a Settings model:

class Gmail(GoogleOauth):
    pass

slug = "..." stays as the escape route — set it only to keep a key the class name does not spell, because the slug keys the service_identities row and the connect wire: renaming a class without pinning its slug rekeys the card and orphans the connected identity. The docs say exactly that.

Every derived slug matches the string its row already uses (GitHubApp is renamed Github to keep "github"), so existing installs are untouched — no migration.

The contract stays loud: declaring name raises with the migration hint, declaring title raises, an abstract base that pins a slug raises, and an explicit slug is still validated against the key pattern. The stray-capability probe in doctor now also skips abstract service bases instead of tripping on their missing key.

Wire and mirror move together: ServiceResponse.name → slug, the frontend Service type, SettingsModal, and the oauth-callback broadcast page follow in the same commit. Path values are unchanged — /api/services/gmail and /api/oauth/gmail/connect read as before.