[iOS] Satellite variables return -1 in feature forms (Internal GPS and External Mock)

[IvaKuklica]

Description
On iOS, @position_visible_satellites and @position_used_satellites return -1 in feature forms with both the Internal and the External (Mock) provider. It also doesn't match the GPS info dialog, which shows N/A.
Project: tester-ws-1/test_external_receiver

Environment

• Device: iPhone 15
• OS: iOS 26
• App build: 2026.5.0 (952111)
• Affected providers: Internal, External (Mock)

Steps to reproduce

1. Set the position provider to Internal.
2. Open a feature form whose fields use @position_visible_satellites and @position_used_satellites.
3. Add a feature and check the values.
4. Switch the provider to External (Mock) and repeat steps 2–3.

Actual results
With both providers, @position_visible_satellites and @position_used_satellites return -1, and -1 gets saved to the feature as if it were real data.

Expected results
The variables return real values. If there's no satellite data, they return empty/NULL, matching what the GPS info dialog shows.

Screenshots