Implement incident mode management service and models

- Added IPackRunIncidentModeService interface for managing incident mode activation, deactivation, and status retrieval.
- Created PackRunIncidentModeService class implementing the service interface with methods for activating, deactivating, and escalating incident modes.
- Introduced incident mode status model (PackRunIncidentModeStatus) and related enums for escalation levels and activation sources.
- Developed retention policy, telemetry settings, and debug capture settings models to manage incident mode configurations.
- Implemented SLO breach notification handling to activate incident mode based on severity.
- Added in-memory store (InMemoryPackRunIncidentModeStore) for testing purposes.
- Created comprehensive unit tests for incident mode service, covering activation, deactivation, status retrieval, and SLO breach handling.

src/Web/StellaOps.Web/src/app/features/policy-studio/editor/policy-editor.component.ts

@@ -40,7 +40,7 @@ interface ChecklistItem {
   imports: [CommonModule, RouterLink],
   changeDetection: ChangeDetectionStrategy.OnPush,
   template: `
-    <section class="policy-editor" aria-busy="{{ loadingPack }}">
+    <section class="policy-editor" [attr.aria-busy]="loadingPack">
       <header class="policy-editor__header">
         <div class="policy-editor__title">
           <p class="policy-editor__eyebrow">Policy Studio · Authoring</p>
@@ -640,7 +640,12 @@ export class PolicyEditorComponent implements OnInit, AfterViewInit, OnDestroy {
           ariaLabel: 'Policy DSL editor',
         });
 
-        const contentDisposable = this.editor.onDidChangeModelContent(() => {
+        const editor = this.editor;
+        if (!editor) {
+          return;
+        }
+
+        const contentDisposable = editor.onDidChangeModelContent(() => {
           const value = this.model?.getValue() ?? '';
           this.content$.next(value);
         });