Add new firework category to allow listing a new type of product

Adds "Fontaine" to ARTICLE_CATEGORY_MAPPING with associated type "F2" in `client/src/lib/validation.ts`.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: dec54137-d5a2-4406-8ad4-5f2f9fb110bf
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/0715008c-7244-40f4-befc-26c014852236/e8a2a1e9-170f-40e2-8907-120da22c7543.jpg

client/src/lib/validation.ts

@@ -54,7 +54,8 @@ export const ARTICLE_CATEGORY_MAPPING = {
   "Pétard à composition flash": ["F3"],
   "Fusée": ["F2", "F3"],
   "Chandelle romaine": ["F2", "F3"],
-  "Chandelle monocoup": ["F2", "F3"]
+  "Chandelle monocoup": ["F2", "F3"],
+  "Fontaine": ["F2"]
 } as const;
 
 export const IDENTITY_TYPES = [