fix(rust): broaden Postgres cell decode + cut stream reallocations #1979

Parent

#1848

Goal

Decode remaining Postgres types that showed <TYPE> placeholders (arrays, time/interval, money, inet/mac, geometric, ranges, bits) and avoid per-cell type resolution / batch buffer churn.

Done when

• types_showcase live probe has no angle-bracket type placeholders (except multirange)
• shop.products.tags decodes as JSON string array
• Column decode strategy resolved once from describe