Add sparkline charts to stats cards, use rolling periods, upgrade recharts to v3

Background sparkline area charts on Movies and Episodes cards show watch
activity distribution over the selected period. Periods now use rolling
windows (past 24h/7d/30d/365d) instead of calendar boundaries. Bumped
stats grid breakpoint to lg. Upgraded recharts 2.15.4 → 3.7.0 and fixed
chart.tsx types for v3 (TooltipContentProps, LegendPayload).

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

package.json

@@ -35,7 +35,7 @@
     "react-day-picker": "9.14.0",
     "react-dom": "19.2.4",
     "react-resizable-panels": "4.7.0",
-    "recharts": "2.15.4",
+    "recharts": "3.7.0",
     "shadcn": "3.8.5",
     "sonner": "2.0.7",
     "tailwind-merge": "3.5.0",