[formulus] Remove legacy id-mapping support

[r0ssing]

Component

• formulus (React Native mobile app)
• formulus-formplayer (React web app)
• synkronus (Go backend server)
• synkronus-cli (Command-line utility)
• Documentation
• Other (please specify)

Feature Description

Remove pre-release legacy support for server ingested/wrong row ids...

See instructions below:

Remove legacy observation row-id support (pre–go-live)

Older builds could have Watermelon id ≠ observation_id after pull. The app now aligns them on ingest and keeps dual lookup / merge-by-column for those rows. Before go-live, drop that if you have no production DBs with mixed ids (or after a one-off cleanup).

Preconditions

• Confirm no release channel has users on builds that created “split” rows, or
• Run a one-time local DB migration (dev script / versioned migration): for each observations row where id != observation_id, either delete test data or rewrite id to match observation_id per Watermelon rules (see their docs on changing primary keys—often safer to export/re-import or clear pre-release installs).

Code to simplify/remove

1. WatermelonDBRepo.findObservationRecord
   Remove the method. updateObservation, deleteObservation, and optionally getObservation / markObservationAsSynced should use observationsCollection.find(stableId) only (or keep getObservation’s existing try/find + query only if you still want lookup-by-column for debugging).

2. markObservationsAsSynced
   Revert to a single query: Q.where('id', Q.oneOf(ids)) (ids from sync are domain observationId, which must equal row id).

3. ObservationMapper.observationIdFromDBModel
   Either delete and use model.observationId everywhere (assert non-empty in dev), or keep model.observationId || model.id as a tight fallback with a console.warn if !model.observationId.

4. Tests

   • ObservationMapper.syncIdentity.test.ts can keep asserting observationId column wins when it differs from id only if you still support fat rows in tests; otherwise simplify to id === observationId.
   • Remove any test copy that describes “legacy ingested rows.”

5. Comments
   Search the repo for legacy, observation_id column, findObservationRecord, and clean up.

Quick verification after removal

• npm test
• Manual: create observation → sync → second device pull → edit → push; list/detail show one observation_id, no duplicate server rows.