Rename the application to RegisFlow and update the branding elements

Update application title to "RegisFlow" across client/index.html, Dashboard.tsx, Login.tsx and replit.md.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 91318273-c764-4fd4-be04-bdc12c38af32
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/0715008c-7244-40f4-befc-26c014852236/75b569d4-1b21-43d8-b5b1-0816d59edebd.jpg

client/index.html

@@ -3,7 +3,7 @@
   <head>
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1" />
-    <title>Registre des Ventes de Pétards</title>
+    <title>RegisFlow</title>
     <meta name="description" content="Application de gestion des ventes de feux d'artifice conforme à la réglementation française" />
   </head>
   <body>