feat(ui/scripts): editor support for self/child/parent accessors

Phases 3+4 of the script-scope rollout. Wires the runtime accessors
landed in efba01d through to Monaco completion, diagnostics, and
hover.

New analyzer surface in ScriptAnalysisService:

  String-literal completion contexts (added to TryStringLiteralCompletions):
    Attributes["..."]                       -> SelfAttributes
    Children["..."]                         -> composition names
    Children["X"].Attributes["..."]         -> child template's attributes
    Children["X"].CallScript("...")         -> child template's scripts
    Parent.Attributes["..."]                -> parent template's attributes
    Parent.CallScript("...")                -> parent template's scripts

  Diagnostics:
    SCADA006   Attribute "Typo" is not declared on {this template,
               child composition 'X', the parent}.  (warning)
    SCADA007   Composition "Unknown" is not declared on this template.
               (warning)

  CallShared / CallScript snippet-expansion now routes through the
  child / parent shape catalogs when invoked on Children["X"] /
  Parent — picking a child script accepts `Sample", ${1:count})`.

Contract additions:
  - AttributeShape (Name, Type) record
  - CompositionContext (Name, Attributes, Scripts) record
  - SelfAttributes / Children / Parent fields on DiagnoseRequest,
    CompletionsRequest, HoverRequest, SignatureHelpRequest

ScriptHost (analyzer-side globals) gains stub AttributeBag /
ChildrenBag / CompositionBag types so Roslyn doesn't emit CS0103 on
Attributes / Children / Parent. The stubs are never invoked — only
their signatures are read by the analyzer's compilation pass.

MonacoEditor.razor exposes SelfAttributes / Children / Parent
parameters; GetContext returns them; monaco-init.js forwards all
three on completion / hover / signature-help / diagnostics requests.

TemplateEdit fetches each composition's resolved child template
shape via GetTemplateWithChildrenAsync, and queries GetAllTemplatesAsync
for any single parent that composes the open template. Multi-parent
or no-parent → Parent is suppressed.

11 new xUnit tests on the new completion / diagnostic paths. Total:
149 -> 159.

Browser-verified via curl:
  - Children["..."] suggests composition names
  - Attributes["..."] suggests attributes with type detail
  - Attributes["Typo"] squiggles SCADA006
  - Children["Unknown"] squiggles SCADA007
  - No spurious CS0103 on the new accessors

Hover, signature help, and inlay hints for the new accessors keep
working because they reuse the same dispatch logic.

src/ScadaLink.CentralUI/Components/Pages/Design/TemplateEdit.razor

@@ -92,6 +92,9 @@
     private MonacoEditor? _scriptEditor;
     private IReadOnlyList<ScadaLink.CentralUI.ScriptAnalysis.DiagnosticMarker> _scriptMarkers
         = Array.Empty<ScadaLink.CentralUI.ScriptAnalysis.DiagnosticMarker>();
+    private IReadOnlyList<ScadaLink.CentralUI.ScriptAnalysis.CompositionContext> _editorChildren
+        = Array.Empty<ScadaLink.CentralUI.ScriptAnalysis.CompositionContext>();
+    private ScadaLink.CentralUI.ScriptAnalysis.CompositionContext? _editorParent;
 
     private bool _showCompForm;
     private int _compComposedTemplateId;
@@ -126,6 +129,13 @@
             _scripts = (await TemplateEngineRepository.GetScriptsByTemplateIdAsync(Id)).ToList();
             _compositions = (await TemplateEngineRepository.GetCompositionsByTemplateIdAsync(Id)).ToList();
 
+            // Editor metadata: child compositions + parent (if exactly one).
+            // Powers Attributes["X"] / Children["Y"].Attributes["Z"] /
+            // Parent.Attributes["W"] completion + SCADA006 / SCADA007 diagnostics
+            // in the Monaco editor.
+            _editorChildren = await BuildChildContextsAsync(_compositions);
+            _editorParent = await TryGetParentContextAsync(Id);
+
             _validationResult = null;
         }
         catch (Exception ex)
@@ -662,6 +672,9 @@
                                           DeclaredParameters="@ScriptParameterNames.Parse(_scriptParameters)"
                                           DeclaredParameterShapes="@ScriptParameterNames.ParseShapes(_scriptParameters)"
                                           SiblingScripts="@(_scripts.Select(s => ScadaLink.CentralUI.ScriptAnalysis.ScriptShapeParser.Parse(s.Name, s.ParameterDefinitions, s.ReturnDefinition)).ToArray())"
+                                          SelfAttributes="@(_attributes.Select(a => new ScadaLink.CentralUI.ScriptAnalysis.AttributeShape(a.Name, MapDataType(a.DataType))).ToArray())"
+                                          Children="@_editorChildren"
+                                          Parent="@_editorParent"
                                           MarkersChanged="@(m => { _scriptMarkers = m; StateHasChanged(); })" />
                             <ProblemsPanel Markers="@_scriptMarkers" OnNavigate="@(m => _scriptEditor?.RevealLineAsync(m.StartLineNumber, m.StartColumn) ?? Task.CompletedTask)" />
                         </div>
@@ -970,4 +983,54 @@
         }
         else { _toast.ShowError(result.Error); }
     }
+
+    // ---- Editor metadata builders ----
+
+    private async Task<IReadOnlyList<ScadaLink.CentralUI.ScriptAnalysis.CompositionContext>> BuildChildContextsAsync(
+        IReadOnlyList<ScadaLink.Commons.Entities.Templates.TemplateComposition> comps)
+    {
+        var result = new List<ScadaLink.CentralUI.ScriptAnalysis.CompositionContext>();
+        foreach (var comp in comps)
+        {
+            var composed = await TemplateEngineRepository.GetTemplateWithChildrenAsync(comp.ComposedTemplateId);
+            if (composed == null) continue;
+            result.Add(BuildCompositionContext(comp.InstanceName, composed));
+        }
+        return result;
+    }
+
+    private async Task<ScadaLink.CentralUI.ScriptAnalysis.CompositionContext?> TryGetParentContextAsync(int templateId)
+    {
+        var all = await TemplateEngineRepository.GetAllTemplatesAsync();
+        var parents = all.Where(t => t.Compositions.Any(c => c.ComposedTemplateId == templateId)).ToList();
+        if (parents.Count != 1) return null; // ambiguous or root — suppress Parent assistance
+        var p = await TemplateEngineRepository.GetTemplateWithChildrenAsync(parents[0].Id);
+        return p == null ? null : BuildCompositionContext(p.Name, p);
+    }
+
+    private static ScadaLink.CentralUI.ScriptAnalysis.CompositionContext BuildCompositionContext(
+        string label,
+        ScadaLink.Commons.Entities.Templates.Template t)
+    {
+        var attrs = t.Attributes
+            .Select(a => new ScadaLink.CentralUI.ScriptAnalysis.AttributeShape(a.Name, MapDataType(a.DataType)))
+            .ToList();
+        var scripts = t.Scripts
+            .Select(s => ScadaLink.CentralUI.ScriptAnalysis.ScriptShapeParser.Parse(
+                s.Name, s.ParameterDefinitions, s.ReturnDefinition))
+            .ToList();
+        return new ScadaLink.CentralUI.ScriptAnalysis.CompositionContext(label, attrs, scripts);
+    }
+
+    private static string MapDataType(ScadaLink.Commons.Types.Enums.DataType dt) => dt switch
+    {
+        ScadaLink.Commons.Types.Enums.DataType.Boolean => "Boolean",
+        ScadaLink.Commons.Types.Enums.DataType.Int32 => "Integer",
+        ScadaLink.Commons.Types.Enums.DataType.Float => "Float",
+        ScadaLink.Commons.Types.Enums.DataType.Double => "Float",
+        ScadaLink.Commons.Types.Enums.DataType.String => "String",
+        ScadaLink.Commons.Types.Enums.DataType.DateTime => "String",
+        ScadaLink.Commons.Types.Enums.DataType.Binary => "Object",
+        _ => "Object"
+    };
 }