[Pg-kit] fix: use opcname instead of amname for index operator class introspection

[sleitor]

Problem

Fixes #5495

When running drizzle-kit pull against PostgreSQL databases with pgvector ivfflat indexes (or other non-default access methods), the generated schema uses the access method name (ivfflat) in the operator class position instead of the actual operator class (e.g. vector_cosine_ops).

Incorrect output:

index("idx").using("ivfflat", table.embedding.asc().nullsLast().op("ivfflat"))

which generates invalid SQL:

CREATE INDEX ... USING ivfflat (embedding ivfflat);

Root Cause

In drizzle-kit/src/dialects/postgres/introspect.ts (and aws-introspect.ts), the opclasses subquery built an array of {oid, name, default} objects for each index column, but used pg_am.amname (the access method name) instead of pg_opclass.opcname (the operator class name).

Fix

Replace pg_am.amname with pg_opclass.opcname in the opclasses subquery, and remove the now-unnecessary JOIN pg_catalog.pg_am from that subquery (the outer query already joins pg_am for the index access method).

Correct output:

index("idx").using("ivfflat", table.embedding.asc().nullsLast().op("vector_cosine_ops"))

which generates valid SQL:

CREATE INDEX ... USING ivfflat (embedding vector_cosine_ops);

Changes

• drizzle-kit/src/dialects/postgres/introspect.ts: use pg_opclass.opcname instead of pg_am.amname, remove unused pg_am JOIN from opclasses subquery
• drizzle-kit/src/dialects/postgres/aws-introspect.ts: same fix
• drizzle-kit/tests/postgres/pull.test.ts: add test for ivfflat index opclass introspection using PGlite's vector extension