Two bugs blocked all Flexoptix stock_observations:
1. db.ts: compatible_brands null param needs ::text[] cast; price_currency needs
::bpchar cast in stock_observations INSERT
2. flexoptix-api-sync.ts: UPDATE transceivers used $1 in WHERE IS NOT NULL clause
without explicit type cast — PostgreSQL cant infer type of untyped null params
in WHERE context. Fixed with $1::text / $2::text casts.
Result: 346 stock observations written on first run after fix.
3ebb552647