fix(ui): add 'use client' to sonner Toaster and chart components

Both files use client-only hooks (useTheme in sonner; useState/useMemo/
useId in chart via React) but the shadcn CLI shipped them without the
'use client' directive. Mounting <Toaster /> in the root server layout
crashed in production with:
  Attempted to call useTheme() from the server but useTheme is on the
  client.

Same risk on chart.tsx once any dashboard page renders <Chart>.

Verified all of src/components/ui/*.tsx — only these two needed the fix.
Future shadcn additions: check 'head -1' for the directive before
importing into server components.

src/components/ui/chart.tsx

@@ -1,3 +1,5 @@
+"use client"
+
 import * as React from "react"
 import * as RechartsPrimitive from "recharts"
 

src/components/ui/sonner.tsx

@@ -1,3 +1,5 @@
+"use client"
+
 import { useTheme } from "next-themes"
 import { Toaster as Sonner, type ToasterProps } from "sonner"