refactor(configdb): delete ConfigGeneration + ClusterNodeGenerationState

Phase 1e of the v2 entity-model rewrite. With the FKs gone (Task 14b) and
the apply pipeline replaced (Task 14c), the v1 draft/publish entities have
no remaining v2 consumers.

Deleted entity classes:
  src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Entities/ConfigGeneration.cs
  src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Entities/ClusterNodeGenerationState.cs

Deleted enum classes (no v2 consumers):
  src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Enums/GenerationStatus.cs
  src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Enums/NodeApplyStatus.cs

OtOpcUaConfigDbContext changes:
  - Removed DbSet<ConfigGeneration> ConfigGenerations
  - Removed DbSet<ClusterNodeGenerationState> ClusterNodeGenerationStates
  - Removed ConfigureConfigGeneration(modelBuilder) call + method body
  - Removed ConfigureClusterNodeGenerationState(modelBuilder) call + body
  - Tidied the "v2 deploy-model tables" header comment

Navigation property cleanup:
  - ServerCluster.Generations collection -> removed
  - ClusterNode.GenerationState navigation -> removed

doc-comment cref cleanup (replaced <see cref="X"/> with <c>X</c> for the
deleted types so the C# XML comment compiler doesn't fail with CS1574):
  - Deployment.cs (cref to ConfigGeneration)
  - NodeDeploymentState.cs (cref to ClusterNodeGenerationState)
  - Core/OpcUa/EquipmentNodeWalker.cs (cref to ConfigGeneration in the
    EquipmentNamespaceContent record's doc-comment; while there, removed
    "All four collections are scoped to the same ConfigGeneration" since
    that's no longer true in v2)

Verification:
  src/Core/ZB.MOM.WW.OtOpcUa.Configuration            -> 0 errors
  src/Core/ZB.MOM.WW.OtOpcUa.Core                     -> 0 errors
  tests/Core/ZB.MOM.WW.OtOpcUa.Configuration.Tests    -> 0 errors
  tests/Core/ZB.MOM.WW.OtOpcUa.Core.Tests             -> 0 errors
  whole solution                                       -> 15 errors
    (all in Server/Admin; transitive Server.Tests/Admin.Tests skip per the
    parent's failure, so the per-project count dropped vs Task 14d's 71)

src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Entities/ClusterNode.cs

@@ -43,5 +43,4 @@ public sealed class ClusterNode
     // Navigation
     public ServerCluster? Cluster { get; set; }
     public ICollection<ClusterNodeCredential> Credentials { get; set; } = [];
-    public ClusterNodeGenerationState? GenerationState { get; set; }
 }

src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Entities/ClusterNodeGenerationState.cs

@@ -1,26 +0,0 @@
-using ZB.MOM.WW.OtOpcUa.Configuration.Enums;
-
-namespace ZB.MOM.WW.OtOpcUa.Configuration.Entities;
-
-/// <summary>
-///     Tracks which generation each node has applied. Per-node (not per-cluster) — both nodes of a
-///     2-node cluster track independently per decision #84.
-/// </summary>
-public sealed class ClusterNodeGenerationState
-{
-    public required string NodeId { get; set; }
-
-    public long? CurrentGenerationId { get; set; }
-
-    public DateTime? LastAppliedAt { get; set; }
-
-    public NodeApplyStatus? LastAppliedStatus { get; set; }
-
-    public string? LastAppliedError { get; set; }
-
-    /// <summary>Updated on every poll for liveness detection.</summary>
-    public DateTime? LastSeenAt { get; set; }
-
-    public ClusterNode? Node { get; set; }
-    public ConfigGeneration? CurrentGeneration { get; set; }
-}

src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Entities/ConfigGeneration.cs

@@ -1,32 +0,0 @@
-using ZB.MOM.WW.OtOpcUa.Configuration.Enums;
-
-namespace ZB.MOM.WW.OtOpcUa.Configuration.Entities;
-
-/// <summary>
-///     Atomic, immutable snapshot of one cluster's configuration.
-///     Per decision #82 — cluster-scoped, not fleet-scoped.
-/// </summary>
-public sealed class ConfigGeneration
-{
-    /// <summary>Monotonically increasing ID, generated by <c>IDENTITY(1, 1)</c>.</summary>
-    public long GenerationId { get; set; }
-
-    public required string ClusterId { get; set; }
-
-    public required GenerationStatus Status { get; set; }
-
-    public long? ParentGenerationId { get; set; }
-
-    public DateTime? PublishedAt { get; set; }
-
-    public string? PublishedBy { get; set; }
-
-    public string? Notes { get; set; }
-
-    public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
-
-    public required string CreatedBy { get; set; }
-
-    public ServerCluster? Cluster { get; set; }
-    public ConfigGeneration? Parent { get; set; }
-}

src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Entities/Deployment.cs

@@ -4,7 +4,7 @@ namespace ZB.MOM.WW.OtOpcUa.Configuration.Entities;
 
 /// <summary>
 ///     Immutable snapshot of a config artifact dispatched to every driver-role node by the
-///     ConfigPublishCoordinator. Replaces the v1 <see cref="ConfigGeneration"/> draft/publish
+///     ConfigPublishCoordinator. Replaces the v1 <c>ConfigGeneration</c> draft/publish
 ///     row; the ArtifactBlob carries the SnapshotAndFlatten() output produced by
 ///     AdminOperationsActor.
 /// </summary>

src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Entities/NodeDeploymentState.cs

@@ -4,7 +4,7 @@ namespace ZB.MOM.WW.OtOpcUa.Configuration.Entities;
 
 /// <summary>
 ///     Per-(node, deployment) apply progress row owned by the DriverHostActor. Replaces the
-///     v1 <see cref="ClusterNodeGenerationState"/> single-row-per-node model with a history
+///     v1 <c>ClusterNodeGenerationState</c> single-row-per-node model with a history
 ///     of every apply attempt so the ConfigPublishCoordinator can reconstruct in-flight state
 ///     after a failover.
 /// </summary>

src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Entities/ServerCluster.cs

@@ -38,5 +38,4 @@ public sealed class ServerCluster
     // Navigation
     public ICollection<ClusterNode> Nodes { get; set; } = [];
     public ICollection<Namespace> Namespaces { get; set; } = [];
-    public ICollection<ConfigGeneration> Generations { get; set; } = [];
 }