What changed

Fixed the dashboard sometimes showing duplicate cards for the same AirPods when other AirPods of the same model are nearby. Previously, a stranger's AirPods could be incorrectly matched to your profile via signal strength alone, even when your profile has identity keys configured.

Technical Context

• Root cause: the signal-quality fallback in the BLE factory did not exclude profiles that have an identity key (IRK). When IRK matching failed for the current scan (e.g. due to BLE address rotation timing), the fallback would match ANY nearby AirPods of the same model to your keyed profile, creating a second card alongside the real IRK-matched one.
• Fix is two-layered: (1) the factory now restricts the signal-quality fallback to profiles without an IRK -- keyed profiles must match via IRK only; (2) DeviceMonitor collapses duplicate live entries for the same IRK-backed profile, preferring the IRK-verified candidate, as a UI safety net.
• A diagnostic WARN log is emitted when a keyed profile would have matched under the old fallback, to help detect stale IRKs in the field.
• For profiles without identity keys, multiple same-profile matches are left intact since they represent genuinely different ambient devices.