Rework ScriptRuntimeContext.ExternalSystem.CachedCall to fit the M3
combined-telemetry model:
* Mints a fresh TrackedOperationId and emits one CachedSubmit packet
via ICachedCallTelemetryForwarder BEFORE handing the call off — the
SiteCalls row is materialised before the first delivery attempt so
Tracking.Status(id) can observe a Submitted row even if immediate
delivery resolves before the helper returns.
* Threads the TrackedOperationId into IExternalSystemClient.CachedCallAsync
as a new optional parameter (and into IDatabaseGateway.CachedWriteAsync
for the Database mirror set up here for E6). The gateway uses the id
as the StoreAndForward messageId so the retry loop (Tasks E4/E5) can
recover it from StoreAndForwardMessage.Id.
* Returns the TrackedOperationId rather than ExternalCallResult — the
script's contract is now "get a tracking handle, observe outcome via
Tracking.Status". Best-effort emission: a thrown forwarder is logged
+ swallowed; the original call still runs and the id is still returned.
DatabaseHelper gets the matching siteId / sourceScript / forwarder
fields and a parallel CachedSubmit emitter (Channel=DbOutbound) so Task
E6's Database.CachedWrite mirror plugs in without further runtime
wiring.
New ICachedCallTelemetryForwarder seam in Commons.Interfaces.Services
so SiteRuntime depends on Commons (existing arrow) rather than
ScadaLink.AuditLog (would have introduced a new dependency).
Bundle E task E3 (and helper-shape work for E6).
