fix: validate email format for partners and members

[mug1sha]

What does this PR do?

This PR adds email format validation to the addPartner and addMember endpoints using a standard regex. It prevents invalid email strings (e.g., "hello") from being persisted to the
database and includes documentation in the README regarding this validation strategy.

Related issue

Closes # (Insert issue number here)

How did you test it?

• Run npm run typecheck to verify the controller changes.
• Run npm test to ensure existing member functionality remains intact.
• Manually verified the regex pattern against standard test cases (valid/invalid emails).

Checklist

• My code builds (npm run build)
• I added or updated tests and npm test passes
• I updated docs/openapi.yaml if I changed any routes
• I added a Prisma migration if I changed schema.prisma
• I updated docs or .env.example if needed

[mug1sha]

validate email format for partners and members fixed @Nick-Lemy @rodriguecyber