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/ICachedCallLifecycleObserver.cs

@@ -57,6 +57,20 @@ public interface ICachedCallLifecycleObserver
 /// <param name="OccurredAtUtc">When this attempt completed.</param>
 /// <param name="DurationMs">Duration of the attempt in milliseconds (null when not measured).</param>
 /// <param name="SourceInstanceId">Originating instance, when known.</param>
+/// <param name="ExecutionId">
+/// Audit Log #23 (ExecutionId Task 4): the originating script execution's
+/// per-run correlation id, threaded through the store-and-forward buffer from
+/// the cached-call enqueue path. The audit bridge stamps it onto the
+/// retry-loop <c>ApiCallCached</c>/<c>DbWriteCached</c> Attempted and
+/// <c>CachedResolve</c> rows so they correlate with the rest of the run.
+/// <c>null</c> for rows buffered before Task 4 (back-compat).
+/// </param>
+/// <param name="SourceScript">
+/// Audit Log #23 (ExecutionId Task 4): the originating script identifier,
+/// threaded alongside <paramref name="ExecutionId"/> so the retry-loop audit
+/// rows carry the same <c>SourceScript</c> provenance the script-side cached
+/// rows already do. <c>null</c> when not known.
+/// </param>
 public sealed record CachedCallAttemptContext(
     TrackedOperationId TrackedOperationId,
     string Channel,
@@ -69,7 +83,9 @@ public sealed record CachedCallAttemptContext(
     DateTime CreatedAtUtc,
     DateTime OccurredAtUtc,
     int? DurationMs,
-    string? SourceInstanceId);
+    string? SourceInstanceId,
+    Guid? ExecutionId = null,
+    string? SourceScript = null);
 
 /// <summary>
 /// Coarse outcome of one cached-call delivery attempt, observed from inside