Update styles for search form submit button

Fix search form - add Enter key handler and form submit

Fix search form - add submit button and fix duplicate filter-tabs

Fix search form - wrap in form element for submit handling

Fix search functionality - form submit + enter key handling

Update Model Hub with new design system

Update style.css - modern design

Update README.md - modern design

Update index.html - modern design

Update app.js - modern design

Upload index.html with huggingface_hub

initial commit