curl --request GET \
  --url https://api.neynar.com/v2/farcaster/storage/usage/ \
  --header 'x-api-key: <api-key>'

{
  "object": "storage_usage",
  "user": {
    "object": "user_dehydrated",
    "fid": 3,
    "username": "<string>",
    "display_name": "<string>",
    "pfp_url": "<string>",
    "custody_address": "0x5a927ac639636e534b678e81768ca19e2c6280b7",
    "score": 123
  },
  "casts": {
    "object": "storage",
    "used": 3659,
    "capacity": 10000
  },
  "reactions": {
    "object": "storage",
    "used": 3659,
    "capacity": 10000
  },
  "links": {
    "object": "storage",
    "used": 3659,
    "capacity": 10000
  },
  "verified_addresses": {
    "object": "storage",
    "used": 3659,
    "capacity": 10000
  },
  "username_proofs": {
    "object": "storage",
    "used": 3659,
    "capacity": 10000
  },
  "signers": {
    "object": "storage",
    "used": 3659,
    "capacity": 10000
  },
  "total_active_units": 2
}