fix: Fix failing integration tests and update documentation

- Fix TestUpdateDevice: Use correct JSON field name and handle float64 type
- Fix TestRejectDeviceRegistration: Expect message response instead of boolean
- Update approve device docs: Add missing response fields
- Update reject device docs: Correct message text and format
- Update Bruno API: Fix example response for reject endpoint

Both integration tests now pass while maintaining API consistency.

docs/developer/api/devices/approve_device_registration.md

@@ -28,8 +28,11 @@ Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
 
 ```json
 {
-  "message": "Device registration approved",
-  "device_id": "uuid"
+  "message": "device approved successfully",
+  "device_name": "string",
+  "device_type": "string", 
+  "registration_id": "uuid",
+  "approved": true
 }
 ```
 

docs/developer/api/devices/reject_device_registration.md

@@ -28,7 +28,7 @@ Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
 
 ```json
 {
-  "message": "Device registration rejected"
+  "message": "device registration rejected"
 }
 ```