merge(deferred-10): aggregated live alarm stream for Alarm Summary

Merges plan #10 (feat/live-alarm-stream) into main alongside plan #22.

Claude-Session: https://claude.ai/code/session_01MtdgwpEeCUn6cUA5f1LMPj

CLAUDE.md

@@ -124,7 +124,7 @@ Other peers in the `scadaproj` family (see `scadaproj/CLAUDE.md` for details): `
 - Inter-cluster communication uses two transports: ClusterClient for command/control (deployments, lifecycle, subscribe/unsubscribe handshake, snapshots) and gRPC server-streaming for real-time data (attribute values, alarm states). Both CentralCommunicationActor and SiteCommunicationActor registered with receptionist. Central creates one ClusterClient per site using NodeA/NodeB as contact points. Sites configure multiple central contact points for failover. Addresses cached in CentralCommunicationActor, refreshed periodically (60s) and on admin changes. Heartbeats serve health monitoring only.
 - gRPC streaming channel: SiteStreamGrpcServer on each site node (Kestrel HTTP/2, port 8083); central creates per-site SiteStreamGrpcClient via SiteStreamGrpcClientFactory. Site entity has GrpcNodeAAddress/GrpcNodeBAddress fields. Proto: sitestream.proto with SiteStreamService, SiteStreamEvent (oneof: AttributeValueUpdate, AlarmStateUpdate). DebugStreamEvent message removed (no longer flows through ClusterClient).
 - Native alarms: a read-only mirror of native alarms from OPC UA Alarms & Conditions servers and the MxAccess Gateway, unified onto an A&C-style condition model (`AlarmConditionState`: orthogonal Active/Acked/Confirmed/Shelved/Suppressed + 0–1000 severity) plus an `AlarmKind` discriminator (Computed/NativeOpcUa/NativeMxAccess). New DCL capability seam `IAlarmSubscribableConnection` (implemented by the OPC UA and MxGateway adapters); the `DataConnectionActor` opens ONE alarm feed per connection and routes transitions to instances by source-object reference. A `NativeAlarmActor` (peer to the computed `AlarmActor` under `InstanceActor`) mirrors one source binding: snapshot atomic-swap on (re)subscribe, retention (drops once inactive+acked), per-source cap, and site SQLite persistence (`native_alarm_state`, survives failover, cleared on redeploy/undeploy — mirrors static overrides). State streams to central over the additively-enriched gRPC `AlarmStateUpdate` (the existing computed `AlarmStateChanged` was enriched additively) and seeds via the DebugView snapshot. Authoring: `TemplateNativeAlarmSource` / `InstanceNativeAlarmSourceOverride` entities flatten to `ResolvedNativeAlarmSource` (inherit/compose/override); management commands + ManagementActor handlers + CLI (`template/instance native-alarm-source`) + Central UI (template editor tab + instance override panel) + enriched DebugView alarm table. Read-only — no ack-back; no central tables.
-- OPC UA / MxGateway UX (M7): operator **Alarm Summary** page (`/monitoring/alarms`, RequireDeployment, read-only) fans out the existing per-instance `DebugViewSnapshot` Ask (SemaphoreSlim-capped, partial-results tolerant) and aggregates client-side — no central alarm store, no aggregated live stream yet (follow-up); shared `AlarmStateBadges` component. OPC UA node browser gains `BrowseNext` continuation paging ("Load more"), a bounded recursive address-space **search** (`IAddressSpaceSearchable` seam; depth + result caps; substring on DisplayName/path), and **type-info** (DataType/ValueRank/Writable on `BrowseNode` for Variables). Attribute-override **CSV bulk import** (`OverrideCsvParser`, all-or-nothing) via InstanceConfigure `InputFile` + CLI `instance import-overrides --file` (native-alarm-source-override CSV deferred). **Verify-endpoint** probe (temporary `RealOpcUaClient`, short timeout, captures an untrusted server cert but NEVER trusts it) + **site-local cert trust**: per-node `CertStoreActor` (runs on every site node, not a singleton) writing the `.der` into the node's OPC UA trusted-peer PKI store; DeploymentManager broadcasts `TrustServerCertCommand`/`RemoveServerCertCommand` to BOTH site nodes so PKI stores stay consistent across failover; Admin-gated cert-management UI (`/design/connections/{id}/certificates`). No central persistence of cert trust (follow-up).
+- OPC UA / MxGateway UX (M7): operator **Alarm Summary** page (`/monitoring/alarms`, RequireDeployment, read-only) fans out the existing per-instance `DebugViewSnapshot` Ask (SemaphoreSlim-capped, partial-results tolerant) and aggregates client-side — no central alarm store; shared `AlarmStateBadges` component. **Aggregated live stream shipped 2026-07-10** (`docs/plans/2026-07-10-aggregated-live-alarm-stream-plan.md`): a transient in-memory per-site central live cache (`ISiteAlarmLiveCache`) fed by a site-wide, alarm-only `SubscribeSite` gRPC stream (seed-then-stream), pushing near-real-time deltas to the page over the Blazor circuit with the 15s poll kept as fallback + NotReporting authority — still no persisted central alarm store. OPC UA node browser gains `BrowseNext` continuation paging ("Load more"), a bounded recursive address-space **search** (`IAddressSpaceSearchable` seam; depth + result caps; substring on DisplayName/path), and **type-info** (DataType/ValueRank/Writable on `BrowseNode` for Variables). Attribute-override **CSV bulk import** (`OverrideCsvParser`, all-or-nothing) via InstanceConfigure `InputFile` + CLI `instance import-overrides --file` (native-alarm-source-override CSV deferred). **Verify-endpoint** probe (temporary `RealOpcUaClient`, short timeout, captures an untrusted server cert but NEVER trusts it) + **site-local cert trust**: per-node `CertStoreActor` (runs on every site node, not a singleton) writing the `.der` into the node's OPC UA trusted-peer PKI store; DeploymentManager broadcasts `TrustServerCertCommand`/`RemoveServerCertCommand` to BOTH site nodes so PKI stores stay consistent across failover; Admin-gated cert-management UI (`/design/connections/{id}/certificates`). No central persistence of cert trust (follow-up).
 
 ### External Integrations
 - External System Gateway: HTTP/REST only, JSON serialization, API key + Basic Auth.