fix(frontend): remove unused React import from Dashboard.tsx

Removes the unused `import React from 'react'` line from Dashboard.tsx
to resolve TS6133 error in lighthouse CI. No other code in the file
references the React namespace.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

src/pages/Dashboard.tsx

@@ -1,4 +1,3 @@
-import React from 'react'
 import { Link } from 'react-router-dom'
 import { authClient } from '../lib/auth-client.ts'
 import { usePurchases, usePriceAlerts } from '../hooks/useApi.ts'