feat: add season annotation bands to Comparison trend chart

Seasons that overlap the current comparison period appear as
colored bands on the Revenue Trend chart, same as Dashboard.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/components/Comparison.tsx

@@ -532,11 +532,53 @@ function Comparison({ data, seasons, showDataLabels, setShowDataLabels, includeV
   }, [data, prevData, currData, ranges, chartMetric, getMetricValue, getPeriodLabel]);
 
   const baseOptions = useMemo(() => createBaseOptions(showDataLabels), [showDataLabels]);
+
+  // Map seasons to annotation bands on the current period's timeline
+  const seasonAnnotations = useMemo(() => {
+    if (!seasons.length) return {};
+    const currStart = new Date(ranges.curr.start);
+    const currEnd = new Date(ranges.curr.end);
+    const annotations: Record<string, unknown> = {};
+    const msPerDay = 1000 * 60 * 60 * 24;
+    const granDivisor = chartGranularity === 'month' ? 30 : chartGranularity === 'week' ? 7 : 1;
+
+    seasons.forEach((s, i) => {
+      const sStart = new Date(s.StartDate);
+      const sEnd = new Date(s.EndDate);
+      // Check overlap with current period
+      if (sEnd < currStart || sStart > currEnd) return;
+
+      const clampedStart = sStart < currStart ? currStart : sStart;
+      const clampedEnd = sEnd > currEnd ? currEnd : sEnd;
+      const startIdx = Math.floor((clampedStart.getTime() - currStart.getTime()) / msPerDay / granDivisor);
+      const endIdx = Math.floor((clampedEnd.getTime() - currStart.getTime()) / msPerDay / granDivisor);
+
+      annotations[`season${i}`] = {
+        type: 'box',
+        xMin: startIdx - 0.5,
+        xMax: endIdx + 0.5,
+        backgroundColor: s.Color + '20',
+        borderColor: s.Color + '40',
+        borderWidth: 1,
+        label: {
+          display: true,
+          content: `${s.Name} ${s.HijriYear}`,
+          position: 'start',
+          color: s.Color,
+          font: { size: 10, weight: '600' },
+          padding: 4
+        }
+      };
+    });
+    return annotations;
+  }, [seasons, ranges.curr, chartGranularity]);
+
   const chartOptions: any = {
     ...baseOptions,
     plugins: {
       ...baseOptions.plugins,
-      legend: { position: 'top', align: 'end', labels: { boxWidth: 12, padding: 12, font: { size: 13 } } }
+      legend: { position: 'top', align: 'end', labels: { boxWidth: 12, padding: 12, font: { size: 13 } } },
+      annotation: { annotations: seasonAnnotations }
     }
   };