refactor: rename ScadaLink → ZB.MOM.WW.ScadaBridge (code + projects + namespaces)

Solution + 23 src projects + 26 test projects renamed; folders, csproj,
namespaces, and ScadaLinkDbContext/ScadaBridgeDbContext class updated.
ActorSystem "scadalink" → "scadabridge", Akka seed-node URLs migrated.
SQL roles/logins, LDAP domains, CLI command name, and CLI config dir
(~/.scadalink → ~/.scadabridge) also renamed.

Build green; 5 Host.Tests fail awaiting SQL login rename in next commit.
Pre-existing StaleTagMonitor timing flakes unchanged.

Rename script committed at tools/rename-to-scadabridge.sh.

src/ZB.MOM.WW.ScadaBridge.ClusterInfrastructure/ClusterOptions.cs

@@ -0,0 +1,79 @@
+namespace ZB.MOM.WW.ScadaBridge.ClusterInfrastructure;
+
+/// <summary>
+/// Cluster configuration model, bound from the <c>ScadaBridge:Cluster</c> section
+/// of <c>appsettings.json</c> via the Options pattern.
+/// <para>
+/// This project owns the cluster <em>configuration contract</em>. The actual
+/// Akka.NET bootstrap — building the HOCON from these values, starting the
+/// <c>ActorSystem</c>, configuring the split-brain resolver and wiring
+/// <c>CoordinatedShutdown</c> — lives in <c>ZB.MOM.WW.ScadaBridge.Host</c>
+/// (see <c>Component-ClusterInfrastructure.md</c> → "Implementation Note — Code Placement").
+/// </para>
+/// <para>
+/// Node-identity settings (remoting hostname/port, cluster role, site identifier,
+/// gRPC port) are deliberately <em>not</em> here — they are owned by
+/// <c>ZB.MOM.WW.ScadaBridge.Host.NodeOptions</c> (<c>ScadaBridge:Node</c> section). Local SQLite
+/// storage paths are owned by the database / store-and-forward options. This class
+/// holds only the cluster-formation and failure-detection settings shared by every node.
+/// </para>
+/// </summary>
+public class ClusterOptions
+{
+    // ClusterInfra-011: the previous `public const string SectionName = "ScadaBridge:Cluster";`
+    // was documented as "single source of truth so binding sites do not hard-code the
+    // magic string" but no caller ever read it — the Host's SiteServiceRegistration and
+    // StartupValidator both hard-code the literal directly. Wiring those binding sites
+    // to reference the constant lives in the Host's edit scope (a separate code-review
+    // task); rather than carry a public constant whose guarantee the code does not
+    // deliver, the constant is removed and the literal stays in the Host until the
+    // Host-side wiring is done. If a future Host change wants the constant back, add it
+    // when the binding sites can be updated in the same commit.
+
+    /// <summary>
+    /// Akka.NET cluster seed nodes. Both nodes are seed nodes — each node lists
+    /// itself and its partner — so either can start first and form the cluster.
+    /// Must contain at least one entry.
+    /// </summary>
+    public List<string> SeedNodes { get; set; } = new();
+
+    /// <summary>
+    /// Split-brain resolver strategy. Must be <c>keep-oldest</c> for the two-node
+    /// clusters ScadaBridge uses: quorum strategies (<c>keep-majority</c>,
+    /// <c>static-quorum</c>) cannot distinguish a crash from a partition with only
+    /// two nodes and would shut down the whole cluster.
+    /// </summary>
+    public string SplitBrainResolverStrategy { get; set; } = "keep-oldest";
+
+    /// <summary>
+    /// Time the cluster membership must remain stable before the split-brain
+    /// resolver acts to down unreachable nodes. Must be positive. Default 15s.
+    /// </summary>
+    public TimeSpan StableAfter { get; set; } = TimeSpan.FromSeconds(15);
+
+    /// <summary>
+    /// Frequency of cluster failure-detector heartbeat messages between nodes.
+    /// Must be well below <see cref="FailureDetectionThreshold"/>. Default 2s.
+    /// </summary>
+    public TimeSpan HeartbeatInterval { get; set; } = TimeSpan.FromSeconds(2);
+
+    /// <summary>
+    /// Time without a heartbeat before a node is considered unreachable
+    /// (Akka's <c>acceptable-heartbeat-pause</c>). Default 10s.
+    /// </summary>
+    public TimeSpan FailureDetectionThreshold { get; set; } = TimeSpan.FromSeconds(10);
+
+    /// <summary>
+    /// Akka's <c>min-nr-of-members</c>. Must be <c>1</c>: after failover only one
+    /// node runs, and a value of <c>2</c> blocks the cluster singleton (Site Runtime
+    /// Deployment Manager) — and therefore all data collection — indefinitely.
+    /// </summary>
+    public int MinNrOfMembers { get; set; } = 1;
+
+    /// <summary>
+    /// The keep-oldest resolver's <c>down-if-alone</c> flag. When <c>true</c> (the
+    /// design-doc requirement), the oldest node downs itself if it finds it has no
+    /// other reachable members, rather than running as an isolated single-node cluster.
+    /// </summary>
+    public bool DownIfAlone { get; set; } = true;
+}