fix(drizzle): generate per-enum filter input types for pg enum columns

[xcfox]

Summary

Fixes #378.

When using drizzleResolverFactory, all PostgreSQL enum columns incorrectly shared a single PgEnumColumnFilters input type. The first enum column processed determined the eq/ne/inArray field types for every other enum column on the same table.

This PR changes enum column filter caching to use the GraphQL enum name (e.g. GenderFilters, EmployeeStatusFilters) instead of the Drizzle column type (PgEnumColumn).

Root cause

columnFilters() cached filter input types by column.columnType. All PostgreSQL enum columns share the same Drizzle column type (PgEnumColumn), so only the first enum column's GraphQL type was used for every subsequent enum filter.

Changes

• Derive filter input names from the GraphQL enum type when the column resolves to a GraphQLEnumType
• Keep existing behavior for non-enum columns (PgTextFilters, PgSerialFilters, etc.)
• Add regression tests covering:
  • Multiple enum columns on one table
  • GraphQL validation against the correct enum in where filters
  • Shared enum reuse across tables/columns
• Update example/documentation schema snapshots (PgEnumColumnFilters → RoleFilters)

Breaking change

PgEnumColumnFilters is replaced with per-enum filter types such as GenderFilters and EmployeeStatusFilters. This is the correct schema shape; clients that referenced PgEnumColumnFilters directly will need to update.

Test plan

• pnpm exec vitest run test/enum-filters.spec.ts test/input-factory.spec.ts test/schema.spec.ts in packages/drizzle
• pnpm run check:type in packages/drizzle
• Verified employees(where: { status: { eq: ACTIVE } }) validates successfully and eq: MALE is rejected