feat: endurance tickets — coûts visibles partout + budget dashboard

Combat: coût 5⚡ affiché, compteur "X combats possibles", bouton disabled
Forge: coût 10⚡ + or affiché (baissé de 15 à 10), bouton disabled
Dashboard: indicateur budget "X combats · Y forges · Z repos"
Repos: coût 10⚡ affiché, disabled si insuffisant

frontend/src/pages/CombatPage.tsx

@@ -1,8 +1,10 @@
 import { useState } from 'react';
 import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
-import { combatApi } from '../api/endpoints';
+import { combatApi, characterApi } from '../api/endpoints';
 import type { Monster, CombatResult } from '../api/types';
-import { Swords, Trophy, Skull, Clock } from 'lucide-react';
+import { Swords, Trophy, Skull, Clock, Zap } from 'lucide-react';
+
+const COMBAT_COST = 5;
 
 const ATTACK_TYPES = [
   { id: 'melee',  label: 'Mêlée',    emoji: '⚔️',  stat: 'Force × 1.5' },
@@ -84,6 +86,10 @@ export function CombatPage() {
   const [attackType, setAttackType] = useState('melee');
   const [lastResult, setLastResult] = useState<CombatResult | null>(null);
 
+  const { data: char } = useQuery({ queryKey: ['character'], queryFn: characterApi.me });
+  const endurance = (char as any)?.enduranceCurrent ?? (char as any)?.endurance ?? 0;
+  const canFight = endurance >= COMBAT_COST;
+
   const { data: monsters, isLoading } = useQuery({
     queryKey: ['monsters'],
     queryFn: combatApi.monsters,
@@ -150,17 +156,23 @@ export function CombatPage() {
             ))}
           </div>
 
+          {/* Coût endurance */}
+          <div style={{ display: 'flex', alignItems: 'center', justifyContent: 'center', gap: 6, marginBottom: 6, fontSize: 12, color: canFight ? '#5ba4f5' : '#e84040' }}>
+            <Zap size={12} /> Coût : {COMBAT_COST} endurance — Disponible : {endurance}
+            {canFight && <span style={{ color: '#6b7a99' }}>({Math.floor(endurance / COMBAT_COST)} combats possibles)</span>}
+          </div>
+
           {/* Bouton combattre */}
           <button
             className="btn btn-red"
-            style={{ width: '100%', fontSize: 15, padding: '0.75rem' }}
-            disabled={!selectedMonster || fight.isPending}
+            style={{ width: '100%', fontSize: 15, padding: '0.75rem', opacity: canFight ? 1 : 0.5 }}
+            disabled={!selectedMonster || fight.isPending || !canFight}
             onClick={() => fight.mutate()}
           >
             {fight.isPending ? (
               <span><Swords size={14} style={{ display: 'inline', marginRight: 6 }} />Combat…</span>
             ) : (
-              <span>⚔️ Combattre {selectedMonster ? `— ${selectedMonster.name}` : ''}</span>
+              <span>⚔️ Combattre {selectedMonster ? `— ${selectedMonster.name}` : ''} ({COMBAT_COST}⚡)</span>
             )}
           </button>