Pet weight: keep the decimal when writing to the API

[trunten82]

Problem

number.<pet>_peso cannot be set to a fractional weight. The descriptor declares
native_step=0.1, but the write casts to int:

https://github.com/Jezza34000/homeassistant_petkit/blob/main/custom_components/petkit/number.py#L238

native_step=0.1,
...
action=lambda api, device, value: api.send_api_request(
    device.id, PetCommand.PET_UPDATE_SETTING, {"weight": int(value)}
),

So setting 3.2 kg sends {"weight": 3}, the entity reads back its old value, and
it looks to the user as if the write silently failed. For a 3-4 kg cat that is a
5-15% error, and 0.1 kg is exactly the resolution a weight trend needs to be
useful. Present on main and in 1.25.0 - 1.27.0.

Fix

Round to one decimal, matching native_step, instead of truncating.

Verification

Against api.eu-pet.com/latest/pet/updatepetprops with a real account on 1.27.0,
the API accepts a float and echoes it back:

DEBUG [pypetkitapi.client] Control API device=pet id=101401316
      action=pet_update_setting param={'weight': 3.2}
DEBUG [pypetkitapi.client] Command execution success, API response :
      {'id': '101401316', 'name': 'Tea', ..., 'weight': 3.2,
       'weightLabel': 'Normal', 'updatedAt': '2026-07-28T22:32:20.000+0000'}

Confirmed in the PetKit app afterwards (7.1 lb with the app set to imperial,
= 3.2 kg). Three cats set to 3.3 / 3.2 / 4.3 kg, all correct.

Separate issue found while verifying, not addressed here

Worth a look independently: after a successful write the value does not appear
in Home Assistant. Every subsequent coordinator refresh kept reporting the old
weight from the account/family listing, even minutes later and after
homeassistant.update_entity, while the pet record server-side had already been
updated. Only reloading the config entry (a fresh login) surfaced the new value.

The pet data appears to come from the account listing rather than a pet-detail
read, and that listing seems to be served stale after updatepetprops. Happy to
open a separate issue with logs if useful.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Jezza34000]

Hi @trunten82
Thanks for reporting and fixing it !
Tested OK on my side & CI OK
Will be released on next version 👍