feat(frontend): update generated API types and Geschichte routes for JourneyItem model

- api.ts: add GeschichteType, JourneyItem, GeschichteSummary schemas;
  remove documentId param from list endpoint; change list response to
  GeschichteSummary[]; add type + items to Geschichte; remove documents field
- GeschichteEditor: remove DocumentMultiSelect + documentIds from payload
  (journey items are managed via the future Lesereisen editor, not here)
- GET /geschichten page: remove documentId filter from server load + URL logic
- geschichten/new: remove documentId pre-population from server load
- geschichten/[id]: replace g.documents with g.items (document-backed JourneyItems)
- geschichten/new + [id]/edit: remove documentIds from submit payload type

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

frontend/src/lib/geschichte/GeschichteEditor.svelte

@@ -6,33 +6,23 @@ import StarterKit from '@tiptap/starter-kit';
 import { m } from '$lib/paraglide/messages.js';
 import type { components } from '$lib/generated/api';
 import PersonMultiSelect from '$lib/person/PersonMultiSelect.svelte';
-import DocumentMultiSelect from '$lib/document/DocumentMultiSelect.svelte';
 
 type Geschichte = components['schemas']['Geschichte'];
 type Person = components['schemas']['Person'];
-type Document = components['schemas']['Document'];
 
 interface Props {
 	geschichte?: Geschichte | null;
 	initialPersons?: Person[];
-	initialDocuments?: Document[];
 	onSubmit: (payload: {
 		title: string;
 		body: string;
 		status: 'DRAFT' | 'PUBLISHED';
 		personIds: string[];
-		documentIds: string[];
 	}) => Promise<void>;
 	submitting?: boolean;
 }
 
-let {
-	geschichte = null,
-	initialPersons = [],
-	initialDocuments = [],
-	onSubmit,
-	submitting = false
-}: Props = $props();
+let { geschichte = null, initialPersons = [], onSubmit, submitting = false }: Props = $props();
 
 // Initial-state snapshot from incoming props. The editor owns these values
 // after mount; the parent should re-mount the component with a different
@@ -44,9 +34,6 @@ let status: 'DRAFT' | 'PUBLISHED' = $state(geschichte?.status ?? 'DRAFT');
 let selectedPersons: Person[] = $state(
 	geschichte?.persons ? Array.from(geschichte.persons) : initialPersons
 );
-let selectedDocuments: Document[] = $state(
-	geschichte?.documents ? Array.from(geschichte.documents) : initialDocuments
-);
 
 let dirty = $state(false);
 let titleTouched = $state(false);
@@ -122,8 +109,7 @@ async function save(nextStatus: 'DRAFT' | 'PUBLISHED') {
 		title: title.trim(),
 		body,
 		status: nextStatus,
-		personIds: selectedPersons.map((p) => p.id!).filter(Boolean),
-		documentIds: selectedDocuments.map((d) => d.id!).filter(Boolean)
+		personIds: selectedPersons.map((p) => p.id!).filter(Boolean)
 	});
 	dirty = false;
 }
@@ -269,14 +255,6 @@ function exec(action: () => void) {
 			<p class="mb-3 font-sans text-xs text-ink-3">{m.geschichte_editor_personen_hint()}</p>
 			<PersonMultiSelect bind:selectedPersons={selectedPersons} />
 		</section>
-
-		<section class="rounded border border-line bg-surface p-4 shadow-sm">
-			<h2 class="mb-2 font-sans text-xs font-bold tracking-widest text-ink-3 uppercase">
-				{m.geschichte_editor_dokumente_heading()}
-			</h2>
-			<p class="mb-3 font-sans text-xs text-ink-3">{m.geschichte_editor_dokumente_hint()}</p>
-			<DocumentMultiSelect bind:selectedDocuments={selectedDocuments} />
-		</section>
 	</aside>
 </div>