feat(report): per-museum trend lines in PDF report chart

When multiple museums are present, the report trend chart now renders one
colored line per museum plus a bold Total line, mirroring dashboard behavior.
Legend is updated to list each museum with its corresponding color.

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

src/components/Report/reportCharts.tsx

@@ -19,12 +19,14 @@ interface TrendChartProps {
   current: number[];
   previous: number[] | null;
   color: string;
+  series?: Array<{ label: string; color: string; data: number[] }>;
   width?: number;
   height?: number;
 }
 
-export function PdfTrendChart({ labels, current, previous, color, width = 470, height = 155 }: TrendChartProps) {
-  const allValues = [...current, ...(previous ?? [])].filter(v => v > 0);
+export function PdfTrendChart({ labels, current, previous, color, series, width = 470, height = 155 }: TrendChartProps) {
+  const seriesValues = (series ?? []).flatMap(s => s.data);
+  const allValues = [...current, ...(previous ?? []), ...seriesValues].filter(v => v > 0);
   const max = allValues.length > 0 ? Math.max(...allValues) : 1;
   // padL wide enough for y-axis labels like "1.2M"
   const padL = 38, padR = 8, padT = 10, padB = 20;
@@ -66,10 +68,16 @@ export function PdfTrendChart({ labels, current, previous, color, width = 470, h
           stroke="#94a3b8" strokeWidth={1.5} strokeDasharray="4 3" fill="none" />
       )}
 
-      {/* Current period line */}
+      {/* Per-museum series */}
+      {(series ?? []).map(s => s.data.some(v => v > 0) && (
+        <Polyline key={s.label} points={toPoints(s.data)}
+          stroke={s.color} strokeWidth={1.5} fill="none" />
+      ))}
+
+      {/* Current period total line */}
       {current.some(v => v > 0) && (
         <Polyline points={toPoints(current)}
-          stroke={color} strokeWidth={2.5} fill="none" />
+          stroke={color} strokeWidth={series && series.length >= 2 ? 2 : 2.5} fill="none" />
       )}
 
       {/* X-axis week labels */}