Get onboarding coverage

curl -X GET https://app.dacard.ai/api/onboarding/coverage \
  -H "Authorization: Bearer $DACARD_API_KEY"

{
  "trialStartedAt": "2026-04-15T12:00:00Z",
  "trialDaysRemaining": 21,
  "milestones": {
    "welcomeInterview": { "completedAt": "2026-04-15T12:08:00Z" },
    "orgMap": { "completedAt": null, "blocker": "no team registry rows yet" }
  },
  "readOnly": false
}