feat(auth): create modular login component architecture

Auth Layout Architecture

• Create AuthLayout with starry background and DarkVeil effects
• Add random AI agent color selection for visual variety
• Implement consistent glassmorphism design across auth pages

Login Component Refactor

• Restructure login page from 430 lines to 16 lines
• Extract reusable components: LoginCard, LoginHeader, LoginEmailField, LoginPasswordField, LoginActions, LoginButton, LoginFooter
• Create LoginForm component orchestrating all subcomponents
• Improve maintainability and reusability for future auth pages

Code Quality Improvements

• Replace && conditional rendering with ConditionalComponent pattern
• Fix ConditionalComponent usage in itri-wizard navigation buttons
• Ensure consistent conditional rendering across components

CLOSE-[564]