fix: quest progression (events after tx), abandon quest, endurance display

- Events (achievement/community/quest) émis APRÈS la transaction combat
  au lieu de dedans — corrige les quêtes qui ne progressaient pas
- POST /api/quests/abandon/:id — abandonner une quête active
- Frontend: bouton "Abandonner" sur les quêtes actives non complétées
- Fix endurance display (enduranceCurrent field mapping)
- Types Character mis à jour (xpToNextLevel, activeTitle, enduranceCurrent)

frontend/src/api/endpoints.ts

@@ -57,6 +57,7 @@ export const questApi = {
   completed: () => api.get<any[]>('/quests/completed'),
   accept:    (questId: string) => api.post<any>(`/quests/accept/${questId}`),
   claim:     (playerQuestId: string) => api.post<any>(`/quests/claim/${playerQuestId}`),
+  abandon:   (playerQuestId: string) => api.post<any>(`/quests/abandon/${playerQuestId}`),
   arcs:      () => api.get<any[]>('/quests/arcs'),
 };