- redesign temperature converter UI with responsive dark/light theme

- add conversion history functionality with localStorage
- implement temperature presets for common values
- add copy-to-clipboard functionality for conversion results
- create collapsible information panels about temperature scales
- enhance input validation with absolute zero temperature checks
- implement tab navigation between converter and history views
- optimize mobile experience with responsive layout adjustments
- refactor javascript for better organization and maintainability

Author: TobiasMue91