feat(registratie): WP-36 — admin cases page + admin delete

Admin-only overview of all cases across owners + an admin delete, gated by a new
`cases:manage` capability (Authz role→cap + CanManageCases + CasesAdmin gate;
FE capability + guard + nav + role.interceptor prefix — the org-template/stamdata
recipe). Backend adds ApplicationStore.ListAll()/DeleteAny() and GET /admin/cases +
DELETE /admin/cases/{id}; admin delete removes ANY case incl. submitted. Page lives
in registratie/ui (owns the Aanvraag aggregate; reuses aanvraag-view + parse),
routed /beheer/zaken; delete guarded by a native confirm, optimistic with rollback.
Typed client regenerated (documents the new endpoints + owner field).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/src/BigRegister.Api/Domain/Authorization/Authz.cs

@@ -43,7 +43,7 @@ public static class Authz
   public static IReadOnlyList<string> RoleCapabilities(Principal principal) => principal.Role switch
   {
     PrincipalRole.Approver => new[] { "brief:approve", "brief:reject", "brief:send" },
-    PrincipalRole.Admin => new[] { "orgtemplate:edit", "stamdata:edit" },
+    PrincipalRole.Admin => new[] { "orgtemplate:edit", "stamdata:edit", "cases:manage" },
     _ => Array.Empty<string>(),
   };
 
@@ -69,6 +69,11 @@ public static class Authz
   /// the maintenance editor consumes; the actual edit lands as a reviewed PR, not a write here.
   public static bool CanEditStamdata(Principal principal) => principal.Role == PrincipalRole.Admin;
 
+  /// Case management (WP-36): admin-only, resource-independent — same shape as
+  /// org-template / stamdata (role IS the decision). Gates the cross-owner /admin/cases
+  /// list + admin delete.
+  public static bool CanManageCases(Principal principal) => principal.Role == PrincipalRole.Admin;
+
   /// Field-level PII (PRD-0002 §5c, phase P2): the case screen's BIG-nummer ships
   /// masked by default; only the behandelaar (Drafter) composing the case — the actor
   /// whose behandel-scherm shows the field — may reveal it. Role-based in the POC; a