fix(utc/locale): close Theme 2 — 8 UTC / time / locale findings

UTC invariant + culture-safety fixes across UI form binding, audit entity
hydrate, and locale-dependent parses. Highlights:
- CentralUI-026/027: AuditFilterBar / SiteCallsReport / NotificationReport /
  EventLogs now apply SpecifyKind(Local) + ToUniversalTime() at form submit
  so browser-local datetime-local inputs aren't silently treated as UTC.
- Commons-019: AuditEvent.OccurredAtUtc / IngestedAtUtc init-setters
  re-tag any incoming DateTime as Kind=Utc, documenting the invariant.
- CD-018: AuditLogEntityTypeConfiguration adds UTC ValueConverters on the
  *Utc DateTime columns so EF hydrate yields Kind=Utc (SQL Server's
  datetime2 has no Kind metadata, so reads were returning Unspecified).
- CD-020: GetPartitionBoundariesOlderThanAsync now SpecifyKind(Utc) on the
  raw-ADO read, matching the existing defence in AuditLogPartitionMaintenance.
- SEL-021: EventLogQueryService.DateTimeOffset.Parse now uses
  InvariantCulture + AssumeUniversal | AdjustToUniversal.
- SR-023: Convert.ToDouble in ScriptActor + AlarmActor (4 sites) now
  passes InvariantCulture so non-US locales don't mis-parse string values.
- HM-020: CentralHealthAggregator.MarkHeartbeat anchors LastHeartbeatAt to
  max(receivedAt, now) on offline→online so a stale receivedAt can't
  leave a recovered site one tick from re-going-offline.

3 new tests added (AuditLog UTC converter, AuditFilterBar/EventLogs/
NotificationReport-touching CentralUI tests already cover Apply paths,
heartbeat offline→online). Build clean; ConfigurationDatabase 236,
Commons 330, HealthMonitoring 71, SiteRuntime 301, SiteEventLogging 50,
CentralUI 50 — all green. README regenerated: 104 open (was 112).

code-reviews/SiteRuntime/findings.md

@@ -8,7 +8,7 @@
 | Last reviewed | 2026-05-28 |
 | Reviewer | claude-agent |
 | Commit reviewed | `1eb6e97` |
-| Open findings | 7 |
+| Open findings | 6 |
 
 ## Summary
 
@@ -1149,9 +1149,19 @@ the parent connection inside `AuditingDbConnection.CreateDbCommand`).
 |--|--|
 | Severity | Low |
 | Category | Correctness & logic bugs |
-| Status | Open |
+| Status | Resolved |
 | Location | `src/ScadaLink.SiteRuntime/Actors/ScriptActor.cs:446`, `src/ScadaLink.SiteRuntime/Actors/AlarmActor.cs:340`, `src/ScadaLink.SiteRuntime/Actors/AlarmActor.cs:356`, `src/ScadaLink.SiteRuntime/Actors/AlarmActor.cs:444` |
 
+**Resolution (2026-05-28):** All four call sites
+(`ScriptActor.EvaluateCondition`, `AlarmActor.EvaluateRangeViolation`,
+`AlarmActor.EvaluateRateOfChange`, `AlarmActor.EvaluateHiLo`) now pass
+`CultureInfo.InvariantCulture` to `Convert.ToDouble`, so a string attribute
+value like `"1.5"` parses identically regardless of the host's
+`CurrentCulture`. For purely-numeric inputs the culture argument is a no-op.
+No new test added — existing `ScriptActor` / `AlarmActor` evaluator tests
+continue to pass and the behaviour is identical under the (existing CI's)
+`en-US` locale.
+
 **Description**
 
 `ScriptActor.EvaluateCondition` and the three `AlarmActor` evaluators