GET /api/sleep/night?date=YYYY-MM-DD returns one reconstructed night for
the phase-progression view: the canonical source's stage segments (each
with an absolute start/end span), the per-stage breakdown, the asleep/
in-bed/awake totals, the mid-sleep awakenings count, and same-wake-day
naps surfaced separately. Session-clustered, wake-day-keyed, one
canonical source per night so two sources never overlay. date omitted
returns the most recent night. A view over existing per-stage rows — no
schema, no new measurement type. OpenAPI regenerated.