chore: simplify inspector

[tianzhou]

No description provided.

[Copilot]

Pull Request Overview

This PR simplifies the index inspection logic by eliminating SQL parsing dependencies. The changes move from parsing index definitions using pg_query_go to directly extracting index column information from PostgreSQL's system catalogs.

Key Changes:

• Replaced complex AST-based index definition parsing with direct SQL queries to pg_get_indexdef and indoption array
• Removed dependency on github.com/pganalyze/pg_query_go/v6
• Deleted ~250 lines of parsing helper functions that are no longer needed

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
ir/queries/queries.sql	Extended index query to directly extract column names, positions, and sort directions using PostgreSQL system functions
ir/queries/queries.sql.go	Generated code adding new fields (NumColumns, ColumnDefinitions, ColumnDirections) to GetIndexesForSchemaRow struct
ir/inspector.go	Removed pg_query dependency and replaced parseIndexDefinition with direct iteration over query results; deleted all AST extraction helper functions

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