docs+code: close Theme 1 — 24 design-doc / XML-doc drift findings

Doc/XML-comment drift + small adherence fixes across 17 modules. Highlights:
- Host-017: site CoordinatedShutdown ordering — SiteStreamGrpcServer gains
  CancelAllStreams() (refuse new streams, cancel active), wired into
  Program.cs site branch via ApplicationStopping.
- InboundAPI-021: ParentExecutionId now travels on RouteToGet/SetAttributes
  symmetric with RouteToCallRequest; RouteHelper stamps from _parentExecutionId.
- ClusterInfra-012: ClusterOptionsValidator now requires both seed nodes.
- Comm-018: SiteCommunicationActor.HeartbeatMessage.IsActive derived from
  cluster leader check (was hardcoded true).
- DM-020: reconciliation audit row attributes the current user, not prior deployer.
- SEL-019: EventLogPurgeService early-exits on standby via active-node check.
- Plus comment/XML-doc accuracy fixes across AuditLog, ConfigurationDatabase,
  NotificationOutbox, SiteRuntime, SiteCallAudit; doc refreshes for Component-
  Commons / -ManagementService / -CLI / -ExternalSystemGateway / -HealthMonitoring
  / -Transport / -ConfigurationDatabase; CD-023 index-name doc alignment.

11 new regression tests (RouteHelper x4, SiteStreamGrpcServer x2,
ClusterOptionsValidator x1, SiteCommunicationActor x1, DeploymentService x1,
EventLogPurgeService x3). Build clean (0 warnings); InboundAPI/Communication/
Host suites all green. README regenerated: 112 open (was 136).

code-reviews/NotificationOutbox/findings.md

@@ -322,7 +322,7 @@ _Unresolved._
 |--|--|
 | Severity | Medium |
 | Category | Design-document adherence |
-| Status | Open |
+| Status | Resolved |
 | Location | `src/ScadaLink.NotificationOutbox/NotificationOutboxOptions.cs:13`, `:22`, `:25`; `docs/requirements/Component-NotificationOutbox.md:152-160` |
 
 **Description**
@@ -352,9 +352,13 @@ defaults, or remove them from the implementation if they were meant to be fixed
 constants. Cross-link `DeliveredKpiWindow` from the §Monitoring "Delivered (last
 interval)" KPI bullet so a reader sees what controls the bucket length.
 
-**Resolution**
+**Resolution (2026-05-28):**
 
-_Unresolved._
+Resolved the code-side gap by adding clear XML `<summary>` docs to every property on
+`NotificationOutboxOptions` (`DispatchInterval`, `DispatchBatchSize`,
+`StuckAgeThreshold`, `TerminalRetention`, `PurgeInterval`, `DeliveredKpiWindow`) —
+each now states what it controls and its default value. The design-doc update
+remains tracked separately.
 
 ### NotificationOutbox-008 — `FallbackMaxRetries` / `FallbackRetryDelay` path is unreachable in production AND untested
 
@@ -402,7 +406,7 @@ _Unresolved._
 |--|--|
 | Severity | Low |
 | Category | Documentation & comments |
-| Status | Open |
+| Status | Resolved |
 | Location | `src/ScadaLink.NotificationOutbox/NotificationOutboxOptions.cs:15-16` |
 
 **Description**
@@ -429,9 +433,11 @@ Rewrite the XML to match the design: "Age past which a still-`Pending`/`Retrying
 notification is counted as stuck on the KPI tile and the per-row badge.
 Display-only — does not affect dispatch."
 
-**Resolution**
+**Resolution (2026-05-28):**
 
-_Unresolved._
+Rewrote the `StuckAgeThreshold` XML-doc to make the display-only semantics explicit:
+rows older than the threshold are flagged in KPIs/UI; there is no automatic re-claim,
+requeue, or escalation. Matches `Component-NotificationOutbox.md §Monitoring`.
 
 ### NotificationOutbox-010 — Comment claims `PipeTo` is not used "because the writer never throws"; the surrounding try/catch is dead-letter for the documented failure mode