- Add CenturionReceiver class that provides the Receiver UI interface so
the dongle appears as a parent with the headset indented underneath,
matching how Lightspeed/Unifying receivers display
- Independently probe dongle features via feature_request() on the
CenturionReceiver, separate from headset features via bridge
- Fix bridge notification dispatch: remove incorrect sub_cpl=0xFF filter
that was silently dropping all battery and other notifications
- Fix battery status decoding: charging status is at byte 2 (not byte 1)
of the CENTURION_BATTERY_SOC response
- Detect wired vs wireless by checking for CentPPBridge in discovered
features; wired headsets fall back to standalone Device
- Name the dongle "Centurion Receiver" to distinguish from the headset
- Filter unprintable dongle serial (control characters 0x14-0x1F)
- Update CLI show output with proper receiver/child hierarchy and spacing
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