fix(health): rows 80+73 — unconfigured replication reports null, reconciler presence surfaced

ROW 80 (observability correctness). An unreplicated site published
LocalDbReplicationConnected=false / LocalDbOplogBacklog=0, contradicting the
nullable semantics every doc and the proto already state ("null means no
reading, NOT disconnected with an empty backlog").

Root cause: the replication engine is registered unconditionally and idles
without a peer, so ISyncStatus answers false/0 on a node that was never meant to
replicate, and LocalDbReplicationStatusReporter passed that straight through.
Two consequences: an operator read connected:false on a healthy site as a fault,
and central's null branches — row 33's conditional KPI emission and
sustained-badge anchor exclusion — never received the null they exist for, so
rig site-b/site-c emitted a permanently misleading
localDbReplicationConnected=0 series.

Fix mirrors the SiteEventLogReplicationCheck precedent: the Host evaluates
SiteLocalDbSetup.ReplicationIsConfigured ONCE and passes it to
AddLocalDbReplicationHealthBridge as a third provider; unconfigured
short-circuits the probe to (null, null). HealthMonitoring never reads LocalDb
config itself, and the same captured value now also feeds
SiteEventLogReplicationCheck so the two surfaces cannot disagree.
ISiteHealthCollector.SetLocalDbReplicationStatus widens to bool? — the
non-nullable bool was the type-level root cause (null was inexpressible).
false now means exactly one thing: configured, peer session down = a real fault.

Wire/central/UI needed no change: the proto already carries BoolValue/Int64Value
wrappers and the aggregator + KPI source already branch on null. This makes code
match doc, so no doc claim was weakened.

Watch the trap that caused this: configured-ness is PeerAddress OR ApiKey (only
the dialling half sets a peer address). The pre-existing SiteLocalDbWiringTests
fixture sets ApiKey and IS a replicating node, so its false/0 assertion is
correct and is kept, with a comment saying so; the new
UnreplicatedSiteLocalDbHealthTests fixture is the genuinely-unreplicated one.

ROW 73 (silent loss of self-heal). AkkaHostedService skips
SiteReconciliationActor when no IDeploymentConfigFetcher is resolvable, and that
skip was a lone boot Warning — a node with no self-heal path at all went on
reporting itself perfectly healthy forever.

Adds tri-state SiteHealthReport.StartupReconcilerActive (null = not reported,
i.e. the central self-report or a pre-row-73 site build; true = running;
false = booted without it), latched once at boot by the Host in both branches.
Additive proto field 29 (BoolValue, vendored C# regenerated via
docker/regen-proto.sh centralcontrol; csproj restored, verified empty diff).
The skip branch also raises its log to Error — no configuration makes the
fetcher legitimately absent on a site node — and writes a best-effort
deployment/Error site event so the evidence outlives the boot log.

Central treatment: a "No self-heal" WARNING badge on the site tile, not a
failure. Config still reaches the node via LocalDb replication while it is up;
what it lost is recovery from a deploy that landed while it was down — degraded,
not offline. Only the explicit false is badged (badging null would light up the
whole fleet the moment central is upgraded ahead of the sites), and offline
sites are skipped, matching the replication-backlog badge.

Fail-before evidence: with the row-80 gate behaviourally reverted,
UnreplicatedSite_HealthReport_ReportsNullForBothLocalDbFields fails
"Expected: null / Actual: False" and 3 of the 8 new reporter unit tests fail.

Tests: HealthMonitoring 128, Host 518, CentralUI 1051, Communication 717,
Commons 715, SiteEventLogging 81 — all green.

src/ZB.MOM.WW.ScadaBridge.HealthMonitoring/SiteHealthCollector.cs

@@ -20,8 +20,18 @@ public class SiteHealthCollector : ISiteHealthCollector
     private long _siteEventLogWriteFailures;
     // One volatile tuple rather than two independent fields: a torn read that paired a
     // fresh Connected with a stale backlog would be indistinguishable from a real state.
-    // Null = the reporter has not yet run (or replication is not wired).
-    private volatile Tuple<bool, long?>? _localDbReplicationStatus;
+    // Null = the reporter has not yet run. Once it HAS run, an unreplicated node latches
+    // (null, null) — "no reading" — rather than the inert engine's (false, 0); see
+    // LocalDbReplicationStatusReporter and register row 80.
+    private volatile Tuple<bool?, long?>? _localDbReplicationStatus;
+    // Latched once at boot by the Host (register row 73). A tri-state int rather than a
+    // bool? because `volatile` cannot be applied to Nullable<bool> (a struct) and this is
+    // written on the startup thread but read on the report-sender thread:
+    //   0 = never told  -> report null ("not reported": central self-report, or a test host)
+    //   1 = reconciler spawned
+    //  -1 = reconciler SKIPPED (no IDeploymentConfigFetcher)
+    // Null must stay distinct from -1: "we don't know" is not "self-heal is missing".
+    private volatile int _startupReconcilerActive;
     private readonly ConcurrentDictionary<string, ConnectionHealth> _connectionStatuses = new();
     private readonly ConcurrentDictionary<string, TagResolutionStatus> _tagResolutionCounts = new();
     private readonly ConcurrentDictionary<string, string> _connectionEndpoints = new();
@@ -109,11 +119,17 @@ public class SiteHealthCollector : ISiteHealthCollector
     }
 
     /// <inheritdoc />
-    public void SetLocalDbReplicationStatus(bool connected, long? oplogBacklog)
+    public void SetLocalDbReplicationStatus(bool? connected, long? oplogBacklog)
     {
         _localDbReplicationStatus = Tuple.Create(connected, oplogBacklog);
     }
 
+    /// <inheritdoc />
+    public void SetStartupReconcilerActive(bool active)
+    {
+        _startupReconcilerActive = active ? 1 : -1;
+    }
+
     /// <inheritdoc />
     public void UpdateConnectionHealth(string connectionName, ConnectionHealth health)
     {
@@ -256,6 +272,7 @@ public class SiteHealthCollector : ISiteHealthCollector
         // Single read of the volatile tuple — two reads could straddle a reporter tick and
         // pair a fresh Connected with a stale backlog.
         var localDbReplication = _localDbReplicationStatus;
+        var startupReconciler = _startupReconcilerActive;
 
         // Snapshot current connection and tag resolution state
         var connectionStatuses = new Dictionary<string, ConnectionHealth>(_connectionStatuses);
@@ -307,7 +324,10 @@ public class SiteHealthCollector : ISiteHealthCollector
             // with an empty backlog".
             LocalDbReplicationConnected = localDbReplication?.Item1,
             LocalDbOplogBacklog = localDbReplication?.Item2,
-            SiteStreamAlarmDropCount = Interlocked.Read(ref _siteStreamAlarmDropCount)
+            SiteStreamAlarmDropCount = Interlocked.Read(ref _siteStreamAlarmDropCount),
+            // Tri-state: 0 stays null ("not reported"), which must never collapse into
+            // false ("self-heal is missing"). Register row 73.
+            StartupReconcilerActive = startupReconciler == 0 ? null : startupReconciler > 0
         };
     }
 }