feat(localdb): one-time alarm-historian.db migrator

Copies the pre-consolidation store-and-forward queue into the consolidated
database on first boot, then renames the legacy file aside. Rows are in that
file precisely because the historian could not be reached, so dropping them
on upgrade would discard exactly the alarm audit trail the queue exists to
protect.

Runs last in OnReady, after every RegisterReplicated call. It is the only
thing in OnReady that writes rows, and capture is trigger-based: a migration
that ran before registration would recover the backlog locally and never
replicate a line of it, silently and permanently.

Ids are derived from the payload rather than the plan's mig-{node}-{legacyId}
scheme. Node-prefixing solves the collision the legacy AUTOINCREMENT key
would cause -- node A's row 7 and node B's row 7 are different alarms -- but
it preserves a duplication that should be collapsed instead. A warm pair's
two legacy files OVERLAP: HistorianAdapterActor default-writes while its
redundancy role is unknown, so both nodes accepted the same transitions
during every boot window. Prefixed ids would carry those duplicates into the
merged buffer forever; equal-payload ids converge them. The same property
makes a crash between commit and rename harmless under INSERT OR IGNORE.

OnReady now takes IConfiguration rather than offering an overload that skips
the migration. A wiring mistake that silently discarded a node's undelivered
alarm history is not a mistake worth making possible.

The copy is restricted to the columns the legacy table actually has. Naming
a column an older build never wrote throws "no such column", which would
discard every row in the table rather than the one field.

Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW

src/Core/ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian/AlarmSfSchema.cs

@@ -1,3 +1,5 @@
+using System.Security.Cryptography;
+using System.Text;
 using Microsoft.Data.Sqlite;
 
 namespace ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian;
@@ -35,6 +37,32 @@ public static class AlarmSfSchema
     /// <summary>The single primary-key column.</summary>
     public const string IdColumn = "id";
 
+    /// <summary>
+    ///     Derives a row's primary key from its serialized payload.
+    /// </summary>
+    /// <remarks>
+    ///     <para>
+    ///         Deterministic rather than a fresh GUID, so that the same event arriving twice
+    ///         converges to one row under last-writer-wins instead of duplicating. That happens for
+    ///         real in two places: <c>HistorianAdapterActor</c> default-writes while its redundancy
+    ///         role is unknown, so both nodes of a pair accept the same fanned transition in the
+    ///         window before the first snapshot; and both nodes independently migrate their own
+    ///         legacy queue file, which for a warm pair holds overlapping history.
+    ///     </para>
+    ///     <para>
+    ///         Two genuinely distinct events cannot collide. <c>AlarmHistorianEvent</c> carries a
+    ///         full-precision timestamp alongside the alarm id, transition kind, message and user,
+    ///         so an equal hash means an equal event.
+    ///     </para>
+    /// </remarks>
+    /// <param name="payloadJson">The serialized <c>AlarmHistorianEvent</c>.</param>
+    /// <returns>The row's primary key.</returns>
+    public static string DeriveId(string payloadJson)
+    {
+        ArgumentNullException.ThrowIfNull(payloadJson);
+        return Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(payloadJson)));
+    }
+
     /// <summary>
     ///     Creates the buffer table if it does not already exist. Idempotent.
     /// </summary>