Next.js Better Auth Minimal API Refactor

Problem

Authentication code has proliferated into many helper functions (getUser(), isAdmin(), requireAuth(), getAuthenticatedUser(), etc.) across the codebase, causing:

• Maintenance burden (multiple functions doing similar things)
• Inconsistent patterns across files
• Optional chaining everywhere (user?.name)
• Performance issues (multiple database queries per auth check)

Context / Trigger Conditions