Improve PROVIDER_SETUP_GUIDE.md for first-time users

[Vatsalc26]

Summary

The provider setup guide is accurate, but still a bit dense for a careful first-time user.

Files

• PROVIDER_SETUP_GUIDE.md

Goal

Make the guide easier to follow for a first-time evaluator or contributor without widening any claims.

Done when

• the wording is clearer
• setup steps remain technically correct
• no product claims are widened
• the document reads better for a noncoder or cautious first-time user

Notes

Please comment on this issue before starting so work does not overlap.