fix(document): fix test regressions from DocumentListItem migration

- Use documentService.getDocumentById() in detail_stillReturnsTrainingLabels
  so the Document.full entity graph eager-loads trainingLabels
- Flatten makeItem() factory in DocumentList.svelte.test.ts (nested
  document: {} overrides broke item.id / item.documentDate access)
- Remove { document: {} } wrapper from DocumentMultiSelect.svelte.spec.ts
  mock responses — component now reads body.items directly as flat items
- Flatten single nested item in page.svelte.test.ts document list test

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

frontend/src/routes/DocumentList.svelte.test.ts

@@ -20,29 +20,46 @@ const { default: DocumentList } = await import('./DocumentList.svelte');
 
 afterEach(cleanup);
 
-const sender = { id: 's1', displayName: 'Anna Schmidt' };
-const receiver = { id: 'r1', displayName: 'Bert Meier' };
+const sender = {
+	id: 's1',
+	lastName: 'Schmidt',
+	displayName: 'Anna Schmidt',
+	personType: 'PERSON' as const,
+	familyMember: false
+};
+const receiver = {
+	id: 'r1',
+	lastName: 'Meier',
+	displayName: 'Bert Meier',
+	personType: 'PERSON' as const,
+	familyMember: false
+};
+
+const emptyMatchData = {
+	titleOffsets: [],
+	senderMatched: false,
+	matchedReceiverIds: [],
+	matchedTagIds: [],
+	snippetOffsets: [],
+	summaryOffsets: []
+};
 
 const makeItem = (overrides: Record<string, unknown> = {}) => ({
-	document: {
-		id: 'd1',
-		title: 'Brief 1923',
-		originalFilename: 'b.pdf',
-		documentDate: '1923-04-15',
-		sender,
-		receivers: [receiver],
-		tags: [],
-		thumbnailUrl: null,
-		contentType: 'application/pdf',
-		summary: null,
-		archiveBox: null,
-		archiveFolder: null,
-		location: null,
-		...overrides
-	},
-	matchData: null,
+	id: 'd1',
+	title: 'Brief 1923',
+	originalFilename: 'b.pdf',
+	documentDate: '1923-04-15',
+	sender,
+	receivers: [receiver],
+	tags: [],
+	summary: undefined,
+	archiveBox: undefined,
+	archiveFolder: undefined,
+	location: undefined,
+	matchData: emptyMatchData,
 	completionPercentage: 0,
-	contributors: []
+	contributors: [],
+	...overrides
 });
 
 describe('DocumentList', () => {
@@ -87,8 +104,26 @@ describe('DocumentList', () => {
 		render(DocumentList, {
 			props: {
 				items: [
-					makeItem({ id: 'd1', sender: { id: 's1', displayName: 'Anna Schmidt' } }),
-					makeItem({ id: 'd2', sender: { id: 's2', displayName: 'Bert Meier' } })
+					makeItem({
+						id: 'd1',
+						sender: {
+							id: 's1',
+							lastName: 'Schmidt',
+							displayName: 'Anna Schmidt',
+							personType: 'PERSON',
+							familyMember: false
+						}
+					}),
+					makeItem({
+						id: 'd2',
+						sender: {
+							id: 's2',
+							lastName: 'Meier',
+							displayName: 'Bert Meier',
+							personType: 'PERSON',
+							familyMember: false
+						}
+					})
 				],
 				canWrite: false,
 				sort: 'SENDER' as const

frontend/src/routes/documents/page.svelte.test.ts

@@ -140,15 +140,12 @@ describe('documents/+ page', () => {
 				data: baseData({
 					items: [
 						{
-							document: {
-								id: 'd1',
-								title: 'Brief 1899',
-								status: 'TRANSCRIBED',
-								documentDate: '1899-04-14',
-								summary: '',
-								originalFilename: 'b1.pdf',
-								receivers: []
-							},
+							id: 'd1',
+							title: 'Brief 1899',
+							documentDate: '1899-04-14',
+							originalFilename: 'b1.pdf',
+							receivers: [],
+							tags: [],
 							matchData: {
 								titleOffsets: [],
 								senderMatched: false,