feat(ui): modularisation du css et fidélisation des composants à la maquette figma

- découpage du css par composant (navbar, hero, footer, global)
- ajustement pixel-perfect du footer (newsletter full-bleed, alignements, typographies)
- documentation et commentaires détaillés du code react et css

config/bundles.php

@@ -13,4 +13,6 @@ return [
     Symfony\Bundle\SecurityBundle\SecurityBundle::class => ['all' => true],
     Symfony\Bundle\MonologBundle\MonologBundle::class => ['all' => true],
     Symfony\Bundle\MakerBundle\MakerBundle::class => ['dev' => true],
+    Symfonycasts\TailwindBundle\SymfonycastsTailwindBundle::class => ['all' => true],
+    Symfony\WebpackEncoreBundle\WebpackEncoreBundle::class => ['all' => true],
 ];