Matter: add UniqueID attribute to BridgedDeviceBasicInformation cluster

[Ludovic BOUÉ (lboue)]

Problem

UniqueID became a mandatory attribute in Matter 1.4 for the BridgedDeviceBasicInformation cluster. Its absence causes controllers such as Home Assistant to fail to create entities for bridged endpoints — the controller cannot stably identify a bridged device across re-pairings or bridge restarts, so it refuses to add it.

Changes

MatterDevice.h

• Add kChanged_UniqueID = 1u << 6 to the Changed_t enum; update kChanged_Last to match
• Add void SetUniqueID(const char* uniqueid) declaration
• Add inline char* GetUniqueID() getter
• Add char unique_id[DeviceDescStrSize] protected member

MatterDevice.cpp

• Include em_system.h
• In the constructor, populate unique_id from SYSTEM_GetUnique() using the format "silabs-%016llx", giving each bridged endpoint a stable, hardware-derived identity
• Add Device::SetUniqueID() implementation (mirrors SetSerialNumber)
• Add UniqueID::Id read handler in HandleReadBridgedDeviceBasicAttribute
• Add kChanged_UniqueID block in HandleDeviceStatusChanged to schedule reporting callbacks

Matter.cpp

• Add DECLARE_DYNAMIC_ATTRIBUTE for UniqueID::Id after SerialNumber in bridgedDeviceBasicAttrs

Matter.h

• Bump bridgedDeviceBasicAttrs extern array size from 7 to 8

Note: bridged_device_basic_information_cluster_revision is left at 4, matching the current Matter 1.4 spec revision for this cluster — revision 4 already covers making UniqueID mandatory, so no further bump is needed.

Testing

Cherry-picked from #166 (verified there on an xiao_mg24 running a Matter bridge sketch; Home Assistant successfully discovered and created entities for all bridged endpoints).

[Tamas Jozsi (silabs-bozont)]

Thank you for the quick fix - could you please squash your new commit into the previous one (so that we don't have a broken state on one)? Then I think we're all set for merging.

[Ludovic BOUÉ (lboue)]

Thank you for the quick fix - could you please squash your new commit into the previous one (so that we don't have a broken state on one)? Then I think we're all set for merging.

Done