fix(siteruntime): self-healed and newly-enabled instances now get their DCL connections (register row 85)

An Instance Actor started by a self-heal came up with NO DCL connection actors,
so every tag it subscribed was answered "Unknown connection: <name>" by the DCL
manager indefinitely. Proven live 2026-08-16 by the row-78 close-out probe: the
sweep correctly started the replication-seeded instances, then every subscribe
failed for 6+ min until a second pair restart.

Root cause is narrower than the register assumed. A DCL connection actor is
never created from data_connection_definitions -- that table has no production
reader at all (GetAllDataConnectionDefinitionsAsync is called only by a test).
It exists only as a side effect of starting an instance, from the Connections
map inside that instance's own flattened config, via EnsureDclConnections.

That ensure was the CALLER's job and only two of the four callers made it:

  CreateInstanceActorBatch (boot)   ensured  OK
  ApplyDeployment (deploy)          ensured  OK
  StartStoredInstance               MISSING  <- row-67 ensure-started + row-78 sweep
  HandleEnableResult                MISSING  <- enabling a disabled instance

The two misses are the two paths added after the original pair -- the signature
of a convention living at call sites instead of in the funnel.

It was never replication-specific: the boot load reads only ENABLED configs, so
a node booting with an instance disabled never creates its connections either,
and enabling it afterwards hit the identical dead end on an ordinary
unreplicated site.

Fix: EnsureDclConnections moves into CreateInstanceActor, already documented as
the single Instance Actor creation funnel (it is where the running revision is
stamped for the same reason), and the two caller-side calls are removed. Placed
before the already-exists guard so the two paths that already called it keep
their exact previous semantics. No new message, option or DCL change -- it
reuses EnsureDclConnection's existing per-name hash guard, so steady state is
silent. Structural rather than another guard: a fifth start path cannot forget.

Deliberately NOT done, with rationale in the memo: a sweep pass over
data_connection_definitions. It would not have fixed row 85 (that table is empty
on a site that has only ever received instance deploys), and re-hashing from it
would fight the deploy path over the same per-name hash slot, recreating
connection actors and dropping live subscriptions on a loop. Two residual
sibling gaps (connection-only artifact deploy replicating to a peer that never
adopts it, and the mirror-image removal case) are recorded in the memo and the
component docs as open, not silently skipped.

Tests: SelfHealCreatesDclConnectionTests, 7 tests asserting on the
CreateConnectionCommand messages sent to a recording DCL stand-in. Verified
fail-before against a behavioral revert (call removed from the funnel, restored
at the two original sites): 4 fail / 3 pass, the 3 being steady-state silence
plus two refactor guards that must pass on both sides.

Docs: sweep design memo gains section 7; Component-SiteRuntime,
Component-DataConnectionLayer, docs/components/SiteRuntime and
docs/components/DataConnectionLayer updated (the deploy-flow step ordering in
docs/components/SiteRuntime was stale as written).

tests/ZB.MOM.WW.ScadaBridge.SiteRuntime.Tests/Actors/InstanceSweepSelfHealTests.cs

@@ -6,7 +6,6 @@ using ZB.MOM.WW.ScadaBridge.Commons.Messages.DebugView;
 using ZB.MOM.WW.ScadaBridge.Commons.Messages.Deployment;
 using ZB.MOM.WW.ScadaBridge.Commons.Types.Enums;
 using ZB.MOM.WW.ScadaBridge.Commons.Types.Flattening;
-using ZB.MOM.WW.ScadaBridge.HealthMonitoring;
 using ZB.MOM.WW.ScadaBridge.SiteRuntime.Actors;
 using ZB.MOM.WW.ScadaBridge.SiteRuntime.Persistence;
 using ZB.MOM.WW.ScadaBridge.SiteRuntime.Scripts;
@@ -89,7 +88,7 @@ public class InstanceSweepSelfHealTests : TestKit, IDisposable
         FakeSiteEventLogger? siteLog = null,
         int sweepSeconds = SweepSeconds)
     {
-        var health = new StartupProbe();
+        var health = new DeploymentManagerStartupProbe();
         var dm = ActorOf(Props.Create(() => new DeploymentManagerActor(
             _storage,
             _compilationService,
@@ -511,39 +510,4 @@ public class InstanceSweepSelfHealTests : TestKit, IDisposable
         Assert.True(await InstanceIsRunningAsync(dm, instanceName));
     }
 
-    /// <summary>
-    /// Minimal <see cref="ISiteHealthCollector"/> whose only job is to expose the observable edge
-    /// "the Deployment Manager's startup config load has completed". The manager calls
-    /// <see cref="SetInstanceCounts"/> unconditionally the moment that load finishes — including
-    /// for an empty site — so a non-zero <see cref="ReportCount"/> replaces a wall-clock sleep.
-    /// </summary>
-    private sealed class StartupProbe : ISiteHealthCollector
-    {
-        private int _reports;
-
-        public int ReportCount => Volatile.Read(ref _reports);
-
-        public void SetInstanceCounts(int deployed, int enabled, int disabled) =>
-            Interlocked.Increment(ref _reports);
-
-        public void IncrementScriptError() { }
-        public void IncrementAlarmError() { }
-        public void IncrementDeadLetter() { }
-        public void IncrementSiteAuditWriteFailures() { }
-        public void IncrementAuditRedactionFailure() { }
-        public void UpdateSiteAuditBacklog(Commons.Types.SiteAuditBacklogSnapshot snapshot) { }
-        public void UpdateConnectionHealth(string connectionName, ConnectionHealth health) { }
-        public void RemoveConnection(string connectionName) { }
-        public void UpdateTagResolution(string connectionName, int totalSubscribed, int successfullyResolved) { }
-        public void UpdateConnectionEndpoint(string connectionName, string endpoint) { }
-        public void UpdateTagQuality(string connectionName, int good, int bad, int uncertain) { }
-        public void SetStoreAndForwardDepths(IReadOnlyDictionary<string, int> depths) { }
-        public void SetParkedMessageCount(int count) { }
-        public void SetNodeHostname(string hostname) { }
-        public void SetClusterNodes(IReadOnlyList<Commons.Messages.Health.NodeStatus> nodes) { }
-        public void SetActiveNode(bool isActive) { }
-        public bool IsActiveNode => true;
-        public Commons.Messages.Health.SiteHealthReport CollectReport(string siteId) =>
-            throw new NotSupportedException("Startup probe collects no report.");
-    }
 }