v0.7.5 - README AWS services documentation

[0.7.5] - 2026-03-20

Added

• README.md: new "AWS Services Used — and Why" section explaining each service's role and the on-prem equivalent it replaces — covers Compute, Networking, Storage, Database, and Operations groups

Fixed

• README.md: removed stale reference to scripts/migrate.sh (script does not exist)