fix(review): address reviewer concerns from PR #661

- Replace brittle createdAt===updatedAt isNew() check with a 7-day
  recency window (created within last 7 days = new)
- Add createdAt/updatedAt to searchItem fixture in page.server.spec.ts
  and assert they are propagated to recentDocs
- Replace null timestamps in DocumentListItem test fixtures with a fixed
  LocalDateTime to satisfy the @Schema(required) contract

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

frontend/src/routes/page.server.spec.ts

@@ -403,7 +403,9 @@ describe('home page load — reader branch (isReader = !canWrite && !canAnnotate
 			receivers: [],
 			tags: [],
 			contributors: [],
-			matchData: { titleOffsets: [], senderMatched: false }
+			matchData: { titleOffsets: [], senderMatched: false },
+			createdAt: '2026-05-01T10:00:00Z',
+			updatedAt: '2026-05-10T08:00:00Z'
 		};
 		const mockGet = vi
 			.fn()
@@ -436,6 +438,8 @@ describe('home page load — reader branch (isReader = !canWrite && !canAnnotate
 			expect(result.recentDocs).toHaveLength(1);
 			expect(result.recentDocs[0]).toBeDefined();
 			expect(result.recentDocs[0].id).toBe('d1');
+			expect(result.recentDocs[0].createdAt).toBe('2026-05-01T10:00:00Z');
+			expect(result.recentDocs[0].updatedAt).toBe('2026-05-10T08:00:00Z');
 		}
 	});