Update skills for Postgres IP restrictions and roaringbitmap

[cursor]

Summary

• Updated read-only inventory guidance to capture Postgres IP restriction descriptions plus role/schema scope details.
• Updated the Postgres safety review and best-practices matrix to recommend documented, scoped IP restriction rules where appropriate.
• Added roaringbitmap as a PlanetScale Postgres extension consideration for bitmap-heavy workloads and migration compatibility.

Changelog entries

• https://planetscale.com/changelog/postgres-ip-restrictions-descriptions-role-autocomplete — Postgres IP restriction rules now support descriptions, and the role field autocompletes active PlanetScale-managed roles; the skills should capture and use that context when assessing network posture.
• https://planetscale.com/changelog/postgres-extension-roaringbitmap — PlanetScale Postgres now supports roaringbitmap; extension guidance should include it when compressed bitmap set operations or migration compatibility are relevant.

Verification

• git diff --check HEAD~1..HEAD