Resolve all 622 issues flagged by the enhanced CommentChecker: add missing
<returns> tags (incl. the standard phrasing on non-generic Task methods),
add missing <summary> tags, and replace misused/redundant <inheritdoc/> on
members that override or implement nothing with real documentation.
Documentation-only — no behavior change; solution builds clean.
Adds IAlarmSubscribableConnection to MxGatewayDataConnection (shared session-less
feed, ref-counted), IMxGatewayClient.RunAlarmStreamAsync over the package
StreamAlarmsAsync with internal reconnect, and MxGatewayAlarmMapper
(AlarmFeedMessage/OnAlarmTransitionEvent -> NativeAlarmTransition). Behavior
verified against a live gateway in Task 28; mapper unit-tested.
Implements IDataConnection + IBrowsableDataConnection over the IMxGatewayClient
seam: connect/disconnect with once-only Disconnected guard + background event
loop, subscribe/unsubscribe with tag routing, read/write batch with per-tag
error classification, WriteBatchAndWait, and Galaxy browse mapping. Covers plan
Tasks 6-10. Full unit coverage via FakeMxGatewayClient (12 tests).