feat: comprehensive security and architecture improvements

- Add Zod validation schemas with strong password requirements (12+ chars, complexity)
- Implement rate limiting for authentication endpoints (registration, password reset)
- Remove duplicate MetricCard component, consolidate to ui/metric-card.tsx
- Update README.md to use pnpm commands consistently
- Enhance authentication security with 12-round bcrypt hashing
- Add comprehensive input validation for all API endpoints
- Fix security vulnerabilities in user registration and password reset flows

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/api/dashboard/users/route.ts

@@ -65,7 +65,7 @@ export async function POST(request: NextRequest) {
   }
 
   const tempPassword = crypto.randomBytes(12).toString("base64").slice(0, 12); // secure random initial password
-  
+
   await prisma.user.create({
     data: {
       email,