🐛 (rn-ble) [NO-ISSUE]: Fix BLE scan first emission delay

[OlivierFreyssinet]

📝 Description

Fixes a ~1 second delay before the first scanned BLE device appears in listenToAvailableDevices().

Root cause: In _startScanning(), the inner subject was a BehaviorSubject([]) which immediately emitted an empty []. This consumed the leading edge of throttleTime(1000), opening a 1s window that dropped the first real scan results. The first scanned device only appeared after the throttle window expired (~1s).

Fix: Replaced BehaviorSubject<InternalScannedDevice[]>([]) with ReplaySubject<InternalScannedDevice[]>(1) for the inner scan subject.

• ReplaySubject(1) buffers the last value like BehaviorSubject (needed because the scan callback fires synchronously before switchMap subscribes to the returned observable) but has no initial emission, so the first real scan result passes through throttleTime immediately as the leading edge.
• Connected devices continue to be fetched immediately (from the outer BehaviorSubject's initial emission) and polled every ~1s via the existing setInterval.

❓ Context

• JIRA or GitHub link: NO-ISSUE

✅ Checklist

• Covered by automatic tests — 3 new tests added covering: (1) first scanned device appears immediately, (2) connected devices appear immediately with no scanned devices, (3) connected devices polling continues via interval
• Changeset is provided
• Documentation is up-to-date
• Impact of the changes:
  • First scanned BLE device now appears immediately instead of being delayed by ~1s
  • Connected device polling behavior unchanged
  • No breaking changes to the public API

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Project	Deployment	Actions	Updated (UTC)
device-sdk-ts-sample	Ready	Preview, Comment	Feb 12, 2026 10:51am

1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
doc-device-management-kit	Ignored		Feb 12, 2026 10:51am

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