fix: consolidate pg_stat_statements handling

[jdodson]

Summary

pg:calls and pg:outliers had duplicate setup code and assumed the extension lived in a specific schema. This unifies them and makes both commands work no matter where the extension is installed.

These changes were driven from the data team / Jason Wadsworth: https://salesforce-internal.slack.com/archives/C1N6YD1PG/p1782855687428859

• Both commands now share one helper in lib/pg/extras.ts (removed the duplicate in pg:outliers).
• The helper detects the extension's actual schema and the queries use it, instead of guessing public/heroku_ext.
• pg:outliers --reset now uses that schema too (the aurora/essential path is unchanged).
• Simplified the "extension not installed" error message.
• Updated unit tests.

Type of Change

Breaking Changes (major semver update)

• Add a ! after your change type to denote a change that breaks current behavior

Feature Additions (minor semver update)

• feat: Introduces a new feature to the codebase

Patch Updates (patch semver update)

• fix: Bug fix
• deps: Dependency upgrade
• revert: Revert a previous commit
• chore: Change that does not affect production code
• refactor: Refactoring existing code without changing behavior
• test: Add/update/remove tests

Testing

Notes: npm install && npm run build. Provision a fresh, throwaway Standard-tier classic Postgres DB (standard-0) — it's billed hourly, starts clean, and hits the branch we changed (Essential/Aurora hit the untouched _heroku. branch and won't let you manage extensions). Destroy it when done.

Steps:

1. Create a clean DB and wait for it:

   heroku addons:create heroku-postgresql:standard-0 -a $APP
   heroku pg:wait -a $APP
   

2. Check where pg_stat_statements got installed:

   heroku pg:psql -a $APP -c "SELECT n.nspname FROM pg_extension e JOIN pg_namespace n ON n.oid=e.extnamespace WHERE e.extname='pg_stat_statements';"
   

   • If it's already non-public (e.g. heroku_ext), that's your non-default-schema case for free — skip to step 4.
   • If it's public (or missing), do step 3 to force a custom schema.
3. (Only if step 2 showed public.) Reinstall into a non-default schema:

   heroku pg:psql -a $APP
   DROP EXTENSION IF EXISTS pg_stat_statements;
   CREATE SCHEMA IF NOT EXISTS stats;
   CREATE EXTENSION pg_stat_statements SCHEMA stats;
   \q
   

4. Confirm both commands work against that schema, and --reset too:

   ./bin/run pg:calls -a $APP           # returns rows, no error
   ./bin/run pg:outliers -a $APP        # returns rows, no error
   ./bin/run pg:outliers --reset -a $APP   # succeeds
   

   (Before this PR these failed when the extension wasn't in public.)
5. Confirm the not-installed error:

   heroku pg:psql -a $APP -c 'DROP EXTENSION pg_stat_statements;'
   ./bin/run pg:outliers -a $APP
   

   Expect exactly:

   The pg_stat_statements extension needs to be installed first.
   You can install it by running:
   
       CREATE EXTENSION pg_stat_statements;
   

6. Tear down the test DB:

   heroku addons:destroy heroku-postgresql:standard-0 -a $APP --confirm $APP
   

Screenshots (if applicable)

Related Issues

GitHub issue: https://gus.lightning.force.com/lightning/r/ADM_Work__c/a07EE00002cTDz5YAG/view

[tlowrimore-heroku]

Nice work!