fix(api-surface): close Theme 9 — 27 naming / dead-code / config / hygiene findings

The largest themed batch — small mechanical fixes across 11 modules.

API / message hygiene:
- Comm-020: SiteAddressCacheLoaded now carries IReadOnlyDictionary /
  IReadOnlyList — Akka messages must be immutable.
- Commons-016: BundleSession.MaxUnlockAttempts named constant replaces
  magic 3.
- Commons-018: IOperationTrackingStore + IPartitionMaintenance moved from
  Interfaces/ root to Interfaces/Services/ (namespace preserved — 9
  consumers exceeded the in-prompt move threshold).
- Commons-023: TrackingStatusSnapshot.SourceNode now consistent with the
  trailing-optional-with-default pattern used elsewhere.
- SR-022: AuditingDbCommand.DbConnection.set no longer uses reflection —
  exposes AuditingDbConnection.Inner via internal API surface.

Dead code / config cleanup:
- ClusterInfra-011: decorative SectionName constant deleted.
- ClusterInfra-014: dead AddClusterInfrastructureActors method + its
  "throws-when-called" test deleted.
- Host-021: Microsoft Logging:LogLevel block deleted from appsettings.json
  (dead under Serilog).

Fail-loud over fail-silent:
- DM-021: ResolveSiteIdentifierAsync throws on missing site (was silently
  substituting a DB id).
- DM-022: dropped transient Pending write — record now lands directly in
  InProgress (no UI flicker, one fewer DB write).
- Host-020: LoggerConfigurationFactory emits a Console.Error warning when
  both Serilog:MinimumLevel and ScadaLink:Logging:MinimumLevel are set
  (ScadaLink remains truth per Host-011).
- SnF-022: NotifyCachedCallObserverAsync logs Warning on unparseable
  TrackedOperationId (was silently dropping).
- SnF-023: empty siteId default replaced with $unknown-site sentinel
  + constructor normalisation.

Correctness:
- SCA-001: SupervisorStrategy XML rewritten to match actual
  DefaultDecider/Restart semantics (was claiming Resume).
- SCA-003: OnUpsertAsync now restamps IngestedAtUtc on every upsert.
- SR-021: HandleDeployArtifacts now dispatches an internal
  ApplyArtifactDataConnectionsToDcl message after the SQLite write so
  system-wide artifact-deploy data-connection changes go live
  immediately (was requiring a site restart).
- SnF-020: RetryParkedMessageAsync captures the parked row BEFORE the
  local write so a concurrent delete can't skip standby replication.

Sentinels / naming collisions:
- HM-021: CentralSiteId changed from "central" to "$central"
  (uncollideable — leading $ is forbidden in real SiteIdentifiers).

Doc / surface cleanups:
- SEL-018: FailedWriteCount promoted to ISiteEventLogger; XML softened
  to "Available for future Health Monitoring integration".
- SnF-019: VERIFY outcome — documented parking-after-DefaultMaxRetries
  in Component-StoreAndForward.md + DefaultMaxRetries XML (uniform
  cap; maxRetries:0 is the unbounded escape hatch).
- SnF-021: Component-StoreAndForward.md no longer claims the tracking
  table lives in SnF — it's in SiteRuntime, the interface is in Commons.
- CLI-020: bundle export response parse guarded with try/catch on
  JsonException / KeyNotFoundException / FormatException — emits a
  clean INVALID_RESPONSE exit instead of a stack trace.

Config:
- ClusterInfra-013: intent comment added to "catastrophic config" test.
- Host-016: appsettings.Site.json second CentralContactPoints entry
  removed (was pointing at the SITE's own port); doc-key explains how
  to extend.
- Host-018: NodeName added to both shipped per-role configs (was
  causing SourceNode to be null on audit rows).

UI:
- CentralUI-029: replaced JS.InvokeAsync<int>("eval", …) with an ES
  module import (new wwwroot/js/browser-time.js).
- CentralUI-032: AuditResultsGrid gains a Previous button backed by a
  cursor stack.

10+ new regression tests across the affected projects. Build clean;
all suites green. README regenerated: 6 open (was 33).

Session-to-date: 130 of 136 originally-open Theme findings closed.

code-reviews/Communication/findings.md

@@ -8,7 +8,7 @@
 | Last reviewed | 2026-05-28 |
 | Reviewer | claude-agent |
 | Commit reviewed | `1eb6e97` |
-| Open findings | 3 |
+| Open findings | 2 |
 
 ## Summary
 
@@ -1005,9 +1005,11 @@ the finding.
 |--|--|
 | Severity | Low |
 | Category | Akka.NET conventions |
-| Status | Open |
+| Status | Resolved |
 | Location | `src/ScadaLink.Communication/Actors/CentralCommunicationActor.cs:567` |
 
+**Resolution (2026-05-28):** `SiteAddressCacheLoaded`'s `SiteContacts` payload is now typed as `IReadOnlyDictionary<string, IReadOnlyList<string>>`, enforcing the Akka.NET message-immutability convention at the type level rather than relying on producer discipline. The producer (`LoadSiteAddressesFromDb`) builds the working buckets as before and wraps each inner `List<string>` with `AsReadOnly()` before constructing the message — the freeze is local to the single refresh tick and the cost is negligible. The consumer (`HandleSiteAddressCacheLoaded`) only ever read via `Keys`, foreach-deconstruct, `Select`, `Count` and `ToImmutableHashSet`, all of which are supported by the new read-only types, so no consumer changes were needed. The existing `MalformedSiteAddress_DoesNotAbortRefresh_OtherSitesStillRegistered` and `ClusterClientRouting_RoutesToConfiguredSite` regression tests exercise the producer→consumer flow and continue to pass under the read-only types.
+
 **Description**
 
 The Akka.NET convention is that messages crossing actor boundaries (even