Refactor button components to use unified Button API

[Swopper050]

Summary

This PR refactors button usage across the application to use the enhanced Button and IconButton components from a unified component API, replacing raw HTML <button> elements and improving consistency.

Key Changes

• Enhanced Button Component API:

  • Changed label prop to accept JSXElement instead of just strings, enabling complex content
  • Added support for trailingIcon prop for icons after the label
  • Added shape prop supporting 'square' and 'circle' values
  • Added block prop for full-width buttons
  • Added style prop for inline styles and ref prop for element references
  • Improved loading state handling with better icon/loader precedence
  • Refactored IconButton to share base props with Button for consistency

• Login Page: Replaced native <button> elements with Button component for login and 2FA submit buttons, and back button, using the new isLoading and label props

• Register Page: Replaced native <button> with Button component for the register submit button

• TopBar Component: Converted all navigation buttons (login, register, mobile menu toggle) to use Button and IconButton components with appropriate variants and props

• Admin Users Page: Replaced delete user button with IconButton and create user button with Button component

• Profile Menu: Refactored logout button to use Button component with loading state

• Language Selector: Converted language selection buttons to use Button component

• Modal Component: Replaced close button with Button component using the new shape="circle" prop

• FrozenWorkspaceModal: Replaced action buttons with Button components

• Base Page: Converted sidebar close button to IconButton

• DeleteWorkspaceModal: Replaced cancel button with Button component

• CSS Updates: Added min-height and padding adjustments to .register-btn-submit class to ensure proper button sizing with the new component structure

Implementation Details

• The Button component now intelligently handles loading states by showing a spinner instead of the icon when isLoading is true
• All data-cy attributes were converted to the camelCase dataCy prop for consistency
• The refactoring maintains backward compatibility while providing a more flexible and composable API
• Removed inline Show components for loading states in favor of the component's built-in isLoading prop handling

https://claude.ai/code/session_01WTi6w5JG3VGv8a2EojToMh