feat: quest page frontend — accept, progress, claim, arcs narratifs

Nouvelle page /quests avec icône Scroll dans la sidebar.
Layout: quêtes actives (gauche) + disponibles (droite) + arcs en bas.
Progress bars, boutons accepter/réclamer, badges répétable.
Arc section collapsible avec status par quête.

frontend/src/api/endpoints.ts

@@ -50,6 +50,16 @@ export const craftApi = {
   collect:  (jobId: string)    => api.post<CharacterItem>(`/craft/collect/${jobId}`),
 };
 
+// Quests
+export const questApi = {
+  available: () => api.get<any[]>('/quests/available'),
+  active:    () => api.get<any[]>('/quests/active'),
+  completed: () => api.get<any[]>('/quests/completed'),
+  accept:    (questId: string) => api.post<any>(`/quests/accept/${questId}`),
+  claim:     (playerQuestId: string) => api.post<any>(`/quests/claim/${playerQuestId}`),
+  arcs:      () => api.get<any[]>('/quests/arcs'),
+};
+
 // Forge
 export const forgeApi = {
   upgrade: (characterItemId: string) =>