Get one email-report schedule (Snowflake native app only).

Returns a single email_report schedule (DVT-4266). Requires dashboard:read; recipients is included only for dashboard:write actors (split read model). An artifact schedule's id 404s here — the two surfaces are disjoint.

THIS ROUTE ANSWERS 404 feature-disabled ONLY WHEN THE SURFACE IS OFF, like every other verb under /v1/dashboards/{id}/email-schedules: all seven share the editionCapabilities.unattendedSchedules cell, and DVT-4490 ships it TRUE wherever emailSchedule is true — the normal Snowflake native-app case, answering normally here, not 404. 404 survives only with DVT_UNATTENDED_SCHEDULES_ENABLED=false on both dvt-api and dvt-engine, or on an edition where emailSchedule itself is false. When it does fire it precedes the path parse, so it is identical for a real schedule id and an invented one. Stored rows are unaffected either way. POST /v1/dashboards/{id}/email ("Email me this report now") remains the on-demand alternative regardless. Everything below describes the behavior every non-disabled install returns.