Get instance send-health

Returns the derived **send health** of a device (WhatsApp instance) over a rolling 24-hour window, computed from the instance's real send outcomes. It surfaces WhatsApp's **reach-out time-lock**: when `restricted` is `true` (with `restriction: "reachout_timelock"`), WhatsApp is blocking this number's messages to new/cold contacts — common on new or recently re-created numbers. `available` is `false` when there is no send activity yet in the window. The device must belong to the authenticated token; ownership is enforced.

curl -X GET "https://example.com/devices/string/send-health"

{  "success": true,  "health": {    "device_id": "d3f1a2b4-7c6e-4f01-9a2b-1c2d3e4f5a6b",    "window_hours": 24,    "sent_ok": 128,    "reachout_blocked": 0,    "other_errors": 0,    "total": 128,    "block_rate": 0,    "restricted": false,    "restriction": "",    "available": true  }}

{  "success": false,  "error": "validation failed",  "error_code": "VALIDATION_ERROR",  "timestamp": "2026-06-15T12:00:00Z"}

{  "success": false,  "error": "validation failed",  "error_code": "VALIDATION_ERROR",  "timestamp": "2026-06-15T12:00:00Z"}