Extend MeasurementType with the seven HealthKit-shaped values the iOS
batch ingest needs (HRV, resting HR, active energy, flights climbed,
distance, VO2 max, body temperature) and add APPLE_HEALTH to the
MeasurementSource enum. Sleep duration unit shifts from hours to
minutes so per-stage HKCategorySample rows persist without precision
loss; the new SleepStage enum mirrors the existing GlucoseContext
column shape and a CHECK constraint scopes it to SLEEP_DURATION rows.
The composite unique index `(user_id, type, source, external_id)`
gives the new batch endpoint an idempotent dedup key while the legacy
`(user_id, type, measured_at, source)` index continues to back the
manual UI's no-duplicate-at-the-same-wall-clock guard. NULL externalId
rows stay distinct under Postgres semantics so manual entries never
collide.
Migration is strictly additive: new enum values append, new columns
are nullable, no rows mutate.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
