feature: query performance health checks

[randoneering]

Pull Request Summary

This PR expands query-health coverage in pgFirstAid with high-impact, actionable checks and adds pgTAP validation for each new check across both pg_firstAid() and v_pgfirstaid.

• Added a large set of query-health checks, including active runtime/lock/idle-in-transaction checks plus pg_stat_statements-based workload checks.
• Added pg_stat_statements Extension Missing check with setup guidance for self-hosted PostgreSQL, AWS RDS, GCP Cloud SQL, and Azure PostgreSQL.
• Added pgfirstaid_pg_stat_statements_checks() and wired it into pg_firstAid() + v_pgfirstaid so extension-dependent checks run only when available.
• Updated high pgTAP coverage for all new checks (including conditional assertions); testing/pgTAP/03_high_tests.sql now runs 1..42.
• Updated workflow trigger behavior so integration tests run when a PR is opened.

Type of Change

• New health check
• Bug fix
• Performance improvement
• Documentation update
• Refactoring/code cleanup
• Breaking change

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Related Issues

• Fixes #
• Related to #
• Closes #

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Testing

• Recompiled:
  • pgFirstAid.sql
  • view_pgFirstAid.sql
  • view_pgFirstAid_managed.sql
• Updated testing/pgTAP/03_high_tests.sql plan to 1..42
• Added pgTAP assertions for:
  • the new pg_stat_statements Extension Missing check
  • all conditional pg_stat_statements checks (only required when extension is present)
• Ran:
  • testing/pgTAP/00_setup.sql
  • testing/pgTAP/03_high_tests.sql
  • testing/pgTAP/99_teardown.sql
• Result: all 42 high-level checks passed

PostgreSQL Version Compatibility

Has this code been tested against the following PostgreSQL versions?

• PostgreSQL 15
• PostgreSQL 16
• PostgreSQL 17
• PostgreSQL 18

Testing notes:

Managed Database Platforms

Has this code been deployed and tested on the following platforms?

• Amazon RDS for PostgreSQL
• Google Cloud SQL for PostgreSQL
• Azure Database for PostgreSQL
• Self-managed PostgreSQL

Platform-specific notes:

• Added provider-specific setup guidance and docs for enabling pg_stat_statements on:
  • self-hosted
  • AWS RDS
  • GCP Cloud SQL
  • Azure PostgreSQL
• If pg_stat_statements is missing, pgFirstAid still runs and reports a clear action item.

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Additional Notes

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[randoneering]

Still need to test against AWS, GCP, and Azure. Neon tests passed. Still building out OSUOSL vms for additional self-hosted testing. Thanks OSUOSL!