Move the per-script-execution Guid on ScriptRuntimeContext from
_auditCorrelationId to _executionId, and stamp it into the dedicated
AuditEvent.ExecutionId column on every script-side audit row:
- Sync ApiCall / DbWrite: ExecutionId set; CorrelationId reverts to
null (a sync one-shot call has no operation lifecycle).
- Cached-call script-side rows (CachedSubmit, immediate-completion
ApiCallCached + CachedResolve) and NotifySend: ExecutionId set;
CorrelationId unchanged (per-operation TrackedOperationId /
NotificationId).
Renames the threaded ctor param/field across ExternalSystemHelper,
DatabaseHelper, AuditingDbConnection and AuditingDbCommand, and threads
the id through NotifyHelper/NotifyTarget. The S&F retry-loop cached rows
(CachedCallLifecycleBridge) are out of scope here.
