feat: Add CVSS receipt management endpoints and related functionality

- Introduced new API endpoints for creating, retrieving, amending, and listing CVSS receipts.
- Updated IPolicyEngineClient interface to include methods for CVSS receipt operations.
- Implemented PolicyEngineClient to handle CVSS receipt requests.
- Enhanced Program.cs to map new CVSS receipt routes with appropriate authorization.
- Added necessary models and contracts for CVSS receipt requests and responses.
- Integrated Postgres document store for managing CVSS receipts and related data.
- Updated database schema with new migrations for source documents and payload storage.
- Refactored existing components to support new CVSS functionality.

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

@@ -12,7 +12,7 @@ import jsPDF from './jspdf.stub';
   imports: [CommonModule],
   changeDetection: ChangeDetectionStrategy.OnPush,
   template: `
-    <section class="expl" aria-busy="{{ loading }}">
+    <section class="expl" [attr.aria-busy]="loading">
       <header class="expl__header" *ngIf="result">
         <div>
           <p class="expl__eyebrow">Policy Studio · Explain</p>

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

@@ -9,7 +9,7 @@ import { ActivatedRoute } from '@angular/router';
   imports: [CommonModule, ReactiveFormsModule],
   changeDetection: ChangeDetectionStrategy.OnPush,
   template: `
-    <section class="rb" aria-busy="false">
+    <section class="rb" [attr.aria-busy]="false">
       <header class="rb__header">
         <div>
           <p class="rb__eyebrow">Policy Studio · Rule Builder</p>