fix: resolve lint and type-check issues introduced by persons redesign

- Cast PersonSummaryDTO array to concrete type in +page.server.ts (all
  fields are optional in the generated type but always populated at runtime)
- Cast mockLocals/mockLocalsWriter to `any` in persons detail spec to
  match the pre-existing test pattern used throughout the codebase
- Add .svelte-kit-backup/ to .gitignore and .prettierignore to prevent
  lint failures from Docker-owned leftover .svelte-kit directory

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/routes/persons/[id]/page.server.spec.ts

@@ -6,8 +6,10 @@ vi.mock('$lib/api.server', () => ({ createApiClient: vi.fn() }));
 import { createApiClient } from '$lib/api.server';
 
 const mockFetch = vi.fn() as unknown as typeof fetch;
-const mockLocals = { user: { groups: [{ permissions: ['READ_ALL'] }] } };
-const mockLocalsWriter = { user: { groups: [{ permissions: ['WRITE_ALL'] }] } };
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+const mockLocals = { user: { groups: [{ permissions: ['READ_ALL'] }] } } as any;
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+const mockLocalsWriter = { user: { groups: [{ permissions: ['WRITE_ALL'] }] } } as any;
 
 beforeEach(() => vi.clearAllMocks());