[Preflight] Do not report custom enums as unsupported types

[kvch]

Description

Previously, pgstream check flagged every user-defined enum column as an unsupported type, e.g.:

schema_type_compatibility: "table_name"."column_name"."type": enum type "enum_name" unknown type; Cast the column to a supported type or exclude the table from the migration.

This is a false positive. The check only recognizes types that pgx 's static type map knows by OID, and enum OIDs are database-specific, so enums never resolve. But the Postgres target replicates enum values as text (with the enum type itself replicated via CREATE TYPE), so they migrate fine.

SchemaTypeCompatibilityCheck now skips enum columns. This covers both scalar enums (typtype = 'e') and arrays of enums (typtype = 'b') whose element carries the enum kind.

Type of Change

Please select the relevant option(s):

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📚 Documentation update
• 🔧 Refactoring (no functional changes)
• ⚡ Performance improvement
• 🧪 Test coverage improvement
• 🔨 Build/CI changes
• 🧹 Code cleanup

Testing

• Unit tests added/updated
• Integration tests added/updated
• Manual testing performed
• All existing tests pass

Checklist

• Code follows project style guidelines
• Self-review completed
• Code is well-commented
• Documentation updated where necessary

[github-actions]

Merging this branch will increase overall coverage

Impacted Packages	Coverage Δ	🤖
github.com/xataio/pgstream/pkg/stream/preflight	72.45% (+0.21%)	👍

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Coverage by file

Changed files (no unit tests)

Changed File	Coverage Δ	Total	Covered	Missed	🤖
github.com/xataio/pgstream/pkg/stream/preflight/schema.go	92.80% (+0.18%)	125 (+3)	116 (+3)	9	👍

Please note that the "Total", "Covered", and "Missed" counts above refer to code statements instead of lines of code. The value in brackets refers to the test coverage of that file in the old version of the code.

Changed unit test files

• github.com/xataio/pgstream/pkg/stream/preflight/schema_test.go