Implement Theme State Management

[MalkyDoutsch]

Overview

Set up state management for the dark/light theme using React Context or Redux.

Requirements

• Theme state should be globally accessible
• Support for persisting theme preference to localStorage
• Support for persisting to user settings if authenticated
• Theme preference persists across page reloads

Acceptance Criteria

• Context/Redux store created for theme state
• useTheme hook available for components
• localStorage integration working
• Theme persists on page reload
• Optional: API integration for authenticated users