feat(auditlog): thread ExecutionId through S&F for retry-loop cached rows

The store-and-forward retry loop emits the per-attempt and terminal cached
audit rows (ApiCallCached/DbWriteCached Attempted, CachedResolve) via
CachedCallLifecycleBridge from a CachedCallAttemptContext, not from the
script context. ExecutionId (and SourceScript) were not threaded through the
S&F buffer, so those rows had ExecutionId = null and SourceScript = null.

Thread both, additively, from the cached-call enqueue path:

- StoreAndForwardMessage gains ExecutionId (Guid?) / SourceScript (string?).
- StoreAndForwardStorage adds nullable execution_id / source_script columns
  via an idempotent PRAGMA-probed ALTER TABLE migration; rows persisted by
  an older build read back null (back-compat).
- StoreAndForwardService.EnqueueAsync gains optional executionId /
  sourceScript params, stamped onto the buffered message and surfaced on the
  CachedCallAttemptContext built in the retry loop.
- CachedCallAttemptContext gains ExecutionId / SourceScript.
- CachedCallLifecycleBridge.BuildPacket sets AuditEvent.ExecutionId and
  AuditEvent.SourceScript from the context (replacing the hard-coded
  SourceScript = null and its now-stale comment).
- IExternalSystemClient.CachedCallAsync / IDatabaseGateway.CachedWriteAsync
  gain optional executionId / sourceScript params; ScriptRuntimeContext's
  CachedCall / CachedWrite helpers pass _executionId / _sourceScript.

Script-side cached rows (CachedSubmit, immediate Attempted+Resolve) are
unchanged. All threading is additive — old buffered S&F rows still
deserialize and process with the new fields null.

src/ScadaLink.Commons/Interfaces/Services/IDatabaseGateway.cs

@@ -29,11 +29,24 @@ public interface IDatabaseGateway
     /// <c>null</c> — when omitted the S&amp;F engine mints a fresh GUID and no
     /// M3 telemetry is correlated (pre-M3 caller behaviour).
     /// </param>
+    /// <param name="executionId">
+    /// Audit Log #23 (ExecutionId Task 4): the originating script execution's
+    /// per-run correlation id. When the write is buffered on a transient
+    /// failure this is threaded onto the S&amp;F message so the retry-loop
+    /// cached-write audit rows carry it. <c>null</c> when not threaded.
+    /// </param>
+    /// <param name="sourceScript">
+    /// Audit Log #23 (ExecutionId Task 4): the originating script identifier,
+    /// threaded onto the buffered S&amp;F message alongside
+    /// <paramref name="executionId"/>. <c>null</c> when not known.
+    /// </param>
     Task CachedWriteAsync(
         string connectionName,
         string sql,
         IReadOnlyDictionary<string, object?>? parameters = null,
         string? originInstanceName = null,
         CancellationToken cancellationToken = default,
-        TrackedOperationId? trackedOperationId = null);
+        TrackedOperationId? trackedOperationId = null,
+        Guid? executionId = null,
+        string? sourceScript = null);
 }