API key usage summary

curl -X GET \
  'https://api.boltroute.ai/api/v1/api-keys/usage?from=2025-01-01T00:00:00Z&to=2025-01-07T00:00:00Z'

{
  "user_id": "550e8400-e29b-41d4-a716-446655440000",
  "total_api_keys": 3,
  "api_keys_by_purpose": {
    "zapier": 1,
    "n8n": 1,
    "google_sheets": 0,
    "custom": 1
  },
  "total_requests": 1234,
  "requests_by_purpose": {
    "zapier": 900,
    "n8n": 200,
    "google_sheets": 0,
    "custom": 134
  },
  "last_used_at": "2025-01-07T12:00:00Z",
  "series": [
    {
      "date": "2025-01-01",
      "total_api_keys": 3,
      "api_keys_by_purpose": { "zapier": 1, "n8n": 1, "google_sheets": 0, "custom": 1 },
      "total_requests": 200,
      "requests_by_purpose": { "zapier": 140, "n8n": 30, "google_sheets": 0, "custom": 30 }
    }
  ]
}