chore: organize solution into module folders (Core/Server/Drivers/Client/Tooling)

Group all 69 projects into category subfolders under src/ and tests/ so the
Rider Solution Explorer mirrors the module structure. Folders: Core, Server,
Drivers (with a nested Driver CLIs subfolder), Client, Tooling.

- Move every project folder on disk with git mv (history preserved as renames).
- Recompute relative paths in 57 .csproj files: cross-category ProjectReferences,
  the lib/ HintPath+None refs in Driver.Historian.Wonderware, and the external
  mxaccessgw refs in Driver.Galaxy and its test project.
- Rebuild ZB.MOM.WW.OtOpcUa.slnx with nested solution folders.
- Re-prefix project paths in functional scripts (e2e, compliance, smoke SQL,
  integration, install).

Build green (0 errors); unit tests pass. Docs left for a separate pass.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Server/ZB.MOM.WW.OtOpcUa.Server/HostStatusPublisher.cs

@@ -0,0 +1,143 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+using ZB.MOM.WW.OtOpcUa.Configuration;
+using ZB.MOM.WW.OtOpcUa.Configuration.Entities;
+using ZB.MOM.WW.OtOpcUa.Configuration.Enums;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.Hosting;
+
+namespace ZB.MOM.WW.OtOpcUa.Server;
+
+/// <summary>
+///     Walks every registered driver once per heartbeat interval, asks each
+///     <see cref="IHostConnectivityProbe"/>-capable driver for its current
+///     <see cref="HostConnectivityStatus"/> list, and upserts one
+///     <see cref="DriverHostStatus"/> row per (NodeId, DriverInstanceId, HostName) into the
+///     central config DB. Powers the Admin UI's per-host drill-down page (LMX follow-up #7).
+/// </summary>
+/// <remarks>
+///     <para>
+///         Polling rather than event-driven: simpler, and matches the cadence the Admin UI
+///         consumes. An event-subscription optimization (push on <c>OnHostStatusChanged</c> for
+///         immediate reflection) is a straightforward follow-up but adds lifecycle complexity
+///         — drivers can be registered after the publisher starts, and subscribing to each
+///         one's event on register + unsubscribing on unregister requires DriverHost to expose
+///         lifecycle events it doesn't today.
+///     </para>
+///     <para>
+///         <see cref="DriverHostStatus.LastSeenUtc"/> advances every heartbeat so the Admin UI
+///         can flag stale rows from a crashed Server process independent of
+///         <see cref="DriverHostStatus.State"/> — a Faulted publisher that stops heartbeating
+///         stays Faulted in the DB but its LastSeenUtc ages out, which is the signal
+///         operators actually want.
+///     </para>
+///     <para>
+///         If the DB is unreachable on a given tick, the publisher logs and moves on — it
+///         does not retry or buffer. The next heartbeat picks up the current-state snapshot,
+///         which is more useful than replaying stale transitions after a long outage.
+///     </para>
+/// </remarks>
+public sealed class HostStatusPublisher(
+    DriverHost driverHost,
+    NodeOptions nodeOptions,
+    IServiceScopeFactory scopeFactory,
+    ILogger<HostStatusPublisher> logger) : BackgroundService
+{
+    internal static readonly TimeSpan HeartbeatInterval = TimeSpan.FromSeconds(10);
+
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    {
+        // Wait a short moment at startup so NodeBootstrap's RegisterAsync calls have had a
+        // chance to land. First tick runs immediately after so a freshly-started Server
+        // surfaces its host topology in the Admin UI without waiting a full interval.
+        try { await Task.Delay(TimeSpan.FromSeconds(2), stoppingToken); }
+        catch (OperationCanceledException) { return; }
+
+        while (!stoppingToken.IsCancellationRequested)
+        {
+            try { await PublishOnceAsync(stoppingToken); }
+            catch (OperationCanceledException) { return; }
+            catch (Exception ex)
+            {
+                // Never take down the Server on a publisher failure. Log and continue —
+                // stale-row detection on the Admin side will surface the outage.
+                logger.LogWarning(ex, "Host-status publisher tick failed — will retry next heartbeat");
+            }
+
+            try { await Task.Delay(HeartbeatInterval, stoppingToken); }
+            catch (OperationCanceledException) { return; }
+        }
+    }
+
+    internal async Task PublishOnceAsync(CancellationToken ct)
+    {
+        var driverIds = driverHost.RegisteredDriverIds;
+        if (driverIds.Count == 0) return;
+
+        var now = DateTime.UtcNow;
+        using var scope = scopeFactory.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<OtOpcUaConfigDbContext>();
+
+        foreach (var driverId in driverIds)
+        {
+            var driver = driverHost.GetDriver(driverId);
+            if (driver is not IHostConnectivityProbe probe) continue;
+
+            IReadOnlyList<HostConnectivityStatus> statuses;
+            try { statuses = probe.GetHostStatuses(); }
+            catch (Exception ex)
+            {
+                logger.LogWarning(ex, "Driver {DriverId} GetHostStatuses threw — skipping this tick", driverId);
+                continue;
+            }
+
+            foreach (var status in statuses)
+            {
+                await UpsertAsync(db, driverId, status, now, ct);
+            }
+        }
+
+        await db.SaveChangesAsync(ct);
+    }
+
+    private async Task UpsertAsync(OtOpcUaConfigDbContext db, string driverId,
+        HostConnectivityStatus status, DateTime now, CancellationToken ct)
+    {
+        var mapped = MapState(status.State);
+        var existing = await db.DriverHostStatuses.SingleOrDefaultAsync(r =>
+            r.NodeId == nodeOptions.NodeId
+            && r.DriverInstanceId == driverId
+            && r.HostName == status.HostName, ct);
+
+        if (existing is null)
+        {
+            db.DriverHostStatuses.Add(new DriverHostStatus
+            {
+                NodeId = nodeOptions.NodeId,
+                DriverInstanceId = driverId,
+                HostName = status.HostName,
+                State = mapped,
+                StateChangedUtc = status.LastChangedUtc,
+                LastSeenUtc = now,
+            });
+            return;
+        }
+
+        existing.LastSeenUtc = now;
+        if (existing.State != mapped)
+        {
+            existing.State = mapped;
+            existing.StateChangedUtc = status.LastChangedUtc;
+        }
+    }
+
+    internal static DriverHostState MapState(HostState state) => state switch
+    {
+        HostState.Running => DriverHostState.Running,
+        HostState.Stopped => DriverHostState.Stopped,
+        HostState.Faulted => DriverHostState.Faulted,
+        _ => DriverHostState.Unknown,
+    };
+}