feat: popup liste des villes + balance au clic sur un cluster

Affiche un panneau flottant au clic sur un nœud : liste des villes
du cluster triées par |balance|, balance nette colorée (orange/teal).
Se ferme sur déplacement/zoom de la carte ou via ✕.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/FlowMap.tsx

@@ -260,13 +260,19 @@ export function FlowMap({ arcs, focusCity, onCityClick }: FlowMapProps) {
   // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [corridors, cityNodes, focusCity, tick, mapReady]);
 
-  // Handler de clic : on transmet la première ville du cluster cliqué
+  const [popupIdx, setPopupIdx] = useState<number | null>(null);
+
+  // Ferme le popup sur déplacement/zoom
+  useEffect(() => { setPopupIdx(null); }, [tick]);
+
+  // Handler de clic : ouvre/ferme le popup + focus
   const handleNodeClick = (nodeIdx: number) => {
     if (!svgElements) return;
     const node = svgElements.nodeElems[nodeIdx];
     const firstCity = [...node.cl.cities][0];
     const isCurrentFocus = node.cl.cities.has(focusCity ?? '');
     onCityClick(isCurrentFocus ? null : firstCity);
+    setPopupIdx(popupIdx === nodeIdx ? null : nodeIdx);
   };
 
   return (
@@ -338,6 +344,49 @@ export function FlowMap({ arcs, focusCity, onCityClick }: FlowMapProps) {
           </g>
         </svg>
       )}
+
+      {/* Popup cluster */}
+      {mapReady && svgElements && popupIdx !== null && (() => {
+        const node = svgElements.nodeElems[popupIdx];
+        const cities = [...node.cl.cities].map(name => {
+          const d = cityNodes.get(name);
+          const net = d ? d.received - d.emitted : 0;
+          return { name, net };
+        }).sort((a, b) => Math.abs(b.net) - Math.abs(a.net));
+
+        // Position : décale à droite du cercle, recadre si hors écran
+        const raw = node.cl.cx + node.r + 8;
+        const containerW = containerRef.current?.clientWidth ?? 0;
+        const popupW = 200;
+        const left = raw + popupW > containerW ? node.cl.cx - node.r - 8 - popupW : raw;
+
+        return (
+          <div
+            className="absolute z-[600] bg-[#0a0b0f]/95 border border-[#2e2f3a] rounded-xl p-3 shadow-xl"
+            style={{ left, top: Math.max(4, node.cl.cy - 80), width: popupW, pointerEvents: 'auto' }}
+          >
+            <div className="flex items-center justify-between mb-2">
+              <span className="text-[#4b5563] text-[10px] uppercase tracking-widest">
+                {node.cityCount > 1 ? `${node.cityCount} villes` : 'Ville'}
+              </span>
+              <button
+                onClick={() => setPopupIdx(null)}
+                className="text-[#4b5563] hover:text-white text-xs leading-none ml-2"
+              >✕</button>
+            </div>
+            <div className="space-y-1 max-h-48 overflow-y-auto">
+              {cities.map(({ name, net }) => (
+                <div key={name} className="flex items-center justify-between gap-1">
+                  <span className="text-white text-xs truncate">{name}</span>
+                  <span className={`text-xs font-mono shrink-0 ${net >= 0 ? 'text-[#00acc1]' : 'text-[#ff8f00]'}`}>
+                    {net >= 0 ? '+' : ''}{Math.round(net).toLocaleString('fr-FR')} Ğ1
+                  </span>
+                </div>
+              ))}
+            </div>
+          </div>
+        );
+      })()}
     </div>
   );
 }