Seed loader: JSON-object field values (location/hq) crash batch insert — showcase account/task/field_zoo seeds silently fail #2735

What

On a fresh showcase boot (`objectstack dev` AND in-process `bootStack`), three seed datasets fail to insert:

ERROR Insert operation failed {"object":"showcase_account", ... "select {\"lat\":47.6062,\"lng\":-122.3321} as `hq` ..."}
ERROR Insert operation failed — "Wrong API use : tried to bind a value of an unknown type ([object Object])."

Objects affected: `showcase_account` (`hq` location), `showcase_task` (`location`), `showcase_field_zoo`. The JSON object value is passed RAW to the SQLite driver instead of being serialized, so the whole batch fails and those objects seed ZERO rows (Accounts/Tasks grids look empty; the field-zoo runtime guard rows are missing).

Suspicion

#2680 (route bulk writes through the engine's batch insert path) — the batch path doesn't run the JSON-field serialization the single-insert path had. Single-record inserts of the same shape via REST work.

Repros on a clean main-based tree; unrelated to app metadata changes. The dogfood suite stays green, so no current test asserts these seeds actually landed — worth a regression test asserting seeded row COUNTS (or the seed loader failing loudly per ADR-0049 instead of logging and continuing).