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>

components/ui/skeleton.tsx

@@ -1,4 +1,4 @@
-import { cn } from "@/lib/utils"
+import { cn } from "@/lib/utils";
 
 function Skeleton({ className, ...props }: React.ComponentProps<"div">) {
   return (
@@ -7,7 +7,7 @@ function Skeleton({ className, ...props }: React.ComponentProps<"div">) {
       className={cn("bg-accent animate-pulse rounded-md", className)}
       {...props}
     />
-  )
+  );
 }
 
-export { Skeleton }
+export { Skeleton };