[wasud]

What changed

• ni.patient.observation and ni.encounter.observation (latest observation per patient/encounter and type): ORDER BY … occurrence DESC, id DESC.
• New tests/test_latest_observation.py.
• ni_observation 16.0.0.6.0 → 16.0.0.6.1, so -u recreates the views.

Why

The views use DISTINCT ON (…, type_id) ordered by occurrence only. When two observations of a type share an occurrence (for example two questionnaires mapped to the same type, completed in one transaction), PostgreSQL may return either row. The patient and encounter forms then read a row that the next query no longer returns, and fail with "records … cannot be found".

Found by the Phase 1 data migration pilot (#141, findings comment). The same fix is in the 17.0/18.0/19.0 migration PRs (#156, #157, #158); this is the 16.0 backport for production. Part of P0-4 (#135), epic #131.

How tested

• --test-tags /ni_observation on a fresh 16.0 DB: 27 tests, 0 failed.
• Without the view change, test_same_occurrence_picks_the_last_record fails.
• pre-commit clean.

Notes for reviewer

• No data change: the views are recreated on -u ni_observation.
• Production may already have such ties (questionnaires that write the same observation type). After the update, the forms show the observation with the highest id for that time.