Bluetooth Connection screen accumulates "Unknown device" entries from previous BLE scans (MAC address randomisation)

Nobody has claimed this yet.

**Description**

The Bluetooth Connection screen shows a large and growing list of "Unknown device" entries even when no Bluetooth devices are physically nearby. The entries appear to be stale BLE scan results that are never cleared between sessions. Because BLE devices use MAC address randomisation, each scan of the same physical device generates a new unique MAC, causing duplicate "Unknown device" entries to accumulate in the list indefinitely.

**Environment**
[ ] Staging [x] PROD

**Application (+ app version, build, operating system)**

Mergin Maps mobile 2026.2.0, Android (Samsung Galaxy A53 5G, Android 16)

**Steps to reproduce**

1. Open the app → tap **More** → **Manage GPS receivers**
2. Tap **Connect new receiver** → select **Bluetooth**
3. Observe the device list — even in a location with no Bluetooth devices in range, a large list of "Unknown device" entries with various MAC addresses is displayed

**Actual results**

A long list of "Unknown device" entries with MAC addresses is shown, persisting across sessions even when no devices are nearby. The list grows over time due to MAC address randomisation causing each BLE advertisement to appear as a new unique device.

**Expected results**

The device list should only show devices discovered in the current scan session and should be cleared between sessions. Devices advertising with randomised MACs that cannot be identified as GPS receivers should not be added to the persistent list.

**Screenshots or logs**

https://github.com/user-attachments/assets/dca061f1-1173-4b4c-8424-ff68fa8c7337

*Conclusion*
*Created by Claude and supervised by a human test analyst.*

Start at More → Manage GPS receivers → Connect new receiver → Bluetooth and trace how scan results are collected and retained between sessions. Reproduce the issue on Android with no nearby devices, then verify that each new session shows only current discoveries and does not retain unidentifiable randomised-MAC entries.

Written by the indexing model from the issue text.