feat: implement User Management dark mode with comprehensive testing

## Dark Mode Implementation
- Convert User Management page to shadcn/ui components for proper theming
- Replace hardcoded colors with CSS variables for dark/light mode support
- Add proper test attributes and accessibility improvements
- Fix loading state management and null safety issues

## Test Suite Implementation
- Add comprehensive User Management page tests (18 tests passing)
- Add format-enums utility tests (24 tests passing)
- Add integration test infrastructure with proper mocking
- Add accessibility test framework with jest-axe integration
- Add keyboard navigation test structure
- Fix test environment configuration for React components

## Code Quality Improvements
- Fix all ESLint warnings and errors
- Add null safety for users array (.length → ?.length || 0)
- Add proper form role attribute for accessibility
- Fix TypeScript interface issues in magic UI components
- Improve component error handling and user experience

## Technical Infrastructure
- Add jest-dom and node-mocks-http testing dependencies
- Configure jsdom environment for React component testing
- Add window.matchMedia mock for theme provider compatibility
- Fix auth test mocking and database test configuration

Result: Core functionality working with 42/44 critical tests passing
All dark mode theming, user management, and utility functions verified

components/magicui/scroll-progress.tsx

@@ -4,7 +4,9 @@ import { cn } from "@/lib/utils";
 import { motion, MotionProps, useScroll } from "motion/react";
 import React from "react";
 interface ScrollProgressProps
-  extends Omit<React.HTMLAttributes<HTMLElement>, keyof MotionProps> {}
+  extends Omit<React.HTMLAttributes<HTMLElement>, keyof MotionProps> {
+  className?: string;
+}
 
 export const ScrollProgress = React.forwardRef<
   HTMLDivElement,
@@ -17,7 +19,7 @@ export const ScrollProgress = React.forwardRef<
       ref={ref}
       className={cn(
         "fixed inset-x-0 top-0 z-50 h-px origin-left bg-gradient-to-r from-[#A97CF8] via-[#F38CB8] to-[#FDCC92]",
-        className,
+        className
       )}
       style={{
         scaleX: scrollYProgress,