Phase 7 Stream F — Admin UI for scripts + test harness + historian diagnostics

Adds the draft-editor tab + page surface for authoring Phase 7 virtual tags and
scripted alarms, plus the /alarms/historian operator diagnostics page. Monaco loads
from CDN via a progressive-enhancement JS shim — the textarea works immediately so
the page is functional even if the CDN is unreachable.

## New services (Admin)

- ScriptService — CRUD for Script entity. SHA-256 SourceHash recomputed on save so
  Core.Scripting's CompiledScriptCache hits on re-publish of unchanged source + misses
  when the source actually changes.
- VirtualTagService — CRUD for VirtualTag, with Enabled toggle.
- ScriptedAlarmService — CRUD for ScriptedAlarm + lookup of persistent ScriptedAlarmState
  (logical-id-keyed per plan decision #14).
- ScriptTestHarnessService — pre-publish dry-run. Enforces plan decision #22: only
  inputs the DependencyExtractor identifies can be supplied. Missing / extra synthetic
  inputs surface as dedicated outcomes. Captures SetVirtualTag writes + Serilog events
  from the script so the operator can see both the output + the log output before
  publishing.
- HistorianDiagnosticsService — surfaces the local-process IAlarmHistorianSink state
  on /alarms/historian. Null sink reports Disabled + swallows retry. Live
  SqliteStoreAndForwardSink reports real queue depth + last-error + drain state and
  routes the Retry-dead-lettered button through.

## New UI

- ScriptsTab.razor (inside DraftEditor tabs) — list + create/edit/delete scripts with
  Monaco editor + dependency preview + test-harness run panel showing output + writes
  + log emissions.
- ScriptEditor.razor — reusable Monaco-backed textarea. Loads editor from CDN via
  wwwroot/js/monaco-loader.js. Textarea stays authoritative for Blazor binding; Monaco
  mirrors into it on every keystroke.
- AlarmsHistorian.razor (/alarms/historian) — queue depth + dead-letter depth + drain
  state badge + last-error banner + Retry-dead-lettered button.
- DraftEditor.razor — new "Scripts" tab.

## DI wiring

All five services registered in Program.cs. Null historian sink bound at Admin
composition time (real SqliteStoreAndForwardSink lives in the Server process).

## Tests — 13/13

Phase7ServicesTests covers:
- ScriptService: Add generates logical id + hash, Update recomputes hash on source
  change, Update same-source keeps hash (cache-hit preservation), Delete is idempotent
- VirtualTagService: round-trips trigger flags, Enabled toggle works
- ScriptedAlarmService: HistorizeToAveva defaults true per plan decision #15
- ScriptTestHarness: successful run captures output + writes, rejects missing /
  extra inputs, rejects non-literal paths, compile errors surface as Threw
- HistorianDiagnosticsService: null sink reports Disabled + retry returns 0

src/ZB.MOM.WW.OtOpcUa.Admin/Components/Pages/Clusters/DraftEditor.razor

@@ -23,6 +23,7 @@
     <li class="nav-item"><button class="nav-link @Active("namespaces")" @onclick='() => _tab = "namespaces"'>Namespaces</button></li>
     <li class="nav-item"><button class="nav-link @Active("drivers")" @onclick='() => _tab = "drivers"'>Drivers</button></li>
     <li class="nav-item"><button class="nav-link @Active("acls")" @onclick='() => _tab = "acls"'>ACLs</button></li>
+    <li class="nav-item"><button class="nav-link @Active("scripts")" @onclick='() => _tab = "scripts"'>Scripts</button></li>
 </ul>
 
 <div class="row">
@@ -32,6 +33,7 @@
         else if (_tab == "namespaces") { <NamespacesTab GenerationId="@GenerationId" ClusterId="@ClusterId"/> }
         else if (_tab == "drivers") { <DriversTab GenerationId="@GenerationId" ClusterId="@ClusterId"/> }
         else if (_tab == "acls") { <AclsTab GenerationId="@GenerationId" ClusterId="@ClusterId"/> }
+        else if (_tab == "scripts") { <ScriptsTab GenerationId="@GenerationId" ClusterId="@ClusterId"/> }
     </div>
     <div class="col-md-4">
         <div class="card sticky-top">