fix: col default expression

[tianzhou]

Fix #91

[Copilot]

Pull Request Overview

This PR fixes a bug in handling column default expressions where complex default expressions containing parentheses combined with NOT NULL constraints were being formatted incorrectly (GitHub issue #91). The specific issue was that closing parentheses were being lost before NOT NULL constraints.

Key changes:

• Updated the normalizeDefaultValue function to use regex-based type cast removal that preserves content after the type cast
• Added comprehensive test case for the issue including raw SQL, expected pgschema output, and pg_dump output

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
ir/normalize.go	Modified type cast stripping logic to use regex pattern matching instead of simple string truncation
cmd/dump/dump_integration_test.go	Added integration test for the default expression bug
testdata/dump/issue_91_col_default_expr/raw.sql	Test input SQL demonstrating the problematic default expression pattern
testdata/dump/issue_91_col_default_expr/pgschema.sql	Expected output showing correct formatting with preserved parentheses
testdata/dump/issue_91_col_default_expr/pgdump.sql	Reference pg_dump output for comparison
testdata/dump/issue_91_col_default_expr/manifest.json	Test case metadata and documentation

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