- Add pgsm_table_export.c with comprehensive export functionality
- Support for partitioned pg_stat_monitor table with full API compatibility
- Export top 300 queries per bucket with 1.5KB query text limits
- Add pg_stat_monitor_export() user-callable function
- Create SQL migration (2.3--2.4.sql) for table and indexes
- Update Makefile to include new object file
- Add function declaration to pg_stat_monitor.h
This implements the complete table storage infrastructure while
maintaining full compatibility with existing pg_stat_monitor API.