feat(bulk-edit): extend BulkDocumentEditLayout with mode="edit"

- New FieldLabelBadge component (additive / replace variants, WCAG AA contrast)
- WhoWhenSection: hideDate prop, editMode prop renders badges next to sender
  and receivers, hides the meta_location field
- DescriptionSection: editMode prop renders badges next to tags and archive
  fields; new bindable archiveBox / archiveFolder inputs only in editMode
- PersonTypeahead: optional badge prop forwards to FieldLabelBadge
- FileSwitcherStrip FileEntry: file is now optional, documentId added so
  edit-mode entries reference an existing document by UUID
- BulkDocumentEditLayout: mode prop branches drop zone / read-only title /
  callout / save handler. Edit save chunks 500 IDs per PATCH, stops on chunk
  failure with retry, marks per-document errors as chips, clears the bulk
  selection store on full success.

Refs #225

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

frontend/src/lib/components/document/DescriptionSection.svelte

@@ -1,31 +1,45 @@
 <script lang="ts">
 import { untrack } from 'svelte';
 import TagInput, { type Tag } from '$lib/components/TagInput.svelte';
+import FieldLabelBadge from './FieldLabelBadge.svelte';
 import { m } from '$lib/paraglide/messages.js';
 
 let {
 	tags = $bindable<Tag[]>([]),
 	currentTitle = $bindable(''),
+	documentLocation = $bindable(''),
+	archiveBox = $bindable(''),
+	archiveFolder = $bindable(''),
 	initialTitle = '',
 	initialDocumentLocation = '',
 	initialSummary = '',
 	titleRequired = false,
 	suggestedTitle = '',
-	hideTitle = false
+	hideTitle = false,
+	editMode = false
 }: {
 	tags?: Tag[];
 	currentTitle?: string;
+	documentLocation?: string;
+	archiveBox?: string;
+	archiveFolder?: string;
 	initialTitle?: string;
 	initialDocumentLocation?: string;
 	initialSummary?: string;
 	titleRequired?: boolean;
 	suggestedTitle?: string;
 	hideTitle?: boolean;
+	editMode?: boolean;
 } = $props();
 
 let titleDirty = $state(false);
 currentTitle = untrack(() => initialTitle);
 const titleValue = $derived(titleDirty ? currentTitle : suggestedTitle || currentTitle);
+
+// Initialize controlled location field once from the legacy initial-* props so
+// callers that haven't switched to the bindable form keep their existing
+// pre-fill behaviour.
+documentLocation = untrack(() => documentLocation || initialDocumentLocation);
 </script>
 
 <div class="rounded-sm border border-line bg-surface p-6 shadow-sm">
@@ -67,40 +81,78 @@ const titleValue = $derived(titleDirty ? currentTitle : suggestedTitle || curren
 
 		<!-- Schlagworte (optional) -->
 		<div>
-			<p class="mb-1 block text-sm font-medium text-ink-2">{m.form_label_tags()}</p>
+			<p class="mb-1 block text-sm font-medium text-ink-2">
+				{m.form_label_tags()}
+				{#if editMode}<FieldLabelBadge variant="additive" />{/if}
+			</p>
 			<TagInput bind:tags={tags} />
 			<input type="hidden" name="tags" value={tags.map((t) => t.name).join(',')} />
 		</div>
 
-		<!-- Inhalt (optional) -->
-		<div>
-			<label for="summary" class="mb-1 block text-sm font-medium text-ink-2"
-				>{m.form_label_content()}</label
-			>
-			<textarea
-				id="summary"
-				name="summary"
-				rows="5"
-				placeholder={m.form_placeholder_content()}
-				class="block w-full rounded border border-line p-2 font-serif text-sm shadow-sm focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring"
-				>{initialSummary}</textarea
-			>
-		</div>
+		{#if !editMode}
+			<!-- Inhalt (optional) — not bulk-editable. -->
+			<div>
+				<label for="summary" class="mb-1 block text-sm font-medium text-ink-2"
+					>{m.form_label_content()}</label
+				>
+				<textarea
+					id="summary"
+					name="summary"
+					rows="5"
+					placeholder={m.form_placeholder_content()}
+					class="block w-full rounded border border-line p-2 font-serif text-sm shadow-sm focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring"
+					>{initialSummary}</textarea
+				>
+			</div>
+		{/if}
 
 		<!-- Aufbewahrungsort (optional) -->
-		<div>
+		<div data-testid="description-document-location">
 			<label for="documentLocation" class="mb-1 block text-sm font-medium text-ink-2"
-				>{m.form_label_archive_location()}</label
-			>
+				>{m.form_label_archive_location()}
+				{#if editMode}<FieldLabelBadge variant="replace" />{/if}
+			</label>
 			<input
 				id="documentLocation"
 				type="text"
 				name="documentLocation"
-				value={initialDocumentLocation}
+				bind:value={documentLocation}
 				placeholder={m.form_placeholder_archive_location()}
 				class="block w-full rounded border border-line p-2 text-sm shadow-sm focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring"
 			/>
 			<p class="mt-1 text-xs text-ink-3">{m.form_helper_archive_location()}</p>
 		</div>
+
+		{#if editMode}
+			<!-- Karton (only in editMode — bulk-editable replace) -->
+			<div data-testid="description-archive-box">
+				<label for="archiveBox" class="mb-1 block text-sm font-medium text-ink-2"
+					>Karton
+					<FieldLabelBadge variant="replace" />
+				</label>
+				<input
+					id="archiveBox"
+					type="text"
+					name="archiveBox"
+					bind:value={archiveBox}
+					class="block w-full rounded border border-line p-2 text-sm shadow-sm focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring"
+				/>
+			</div>
+
+			<!-- Mappe (only in editMode — bulk-editable replace) -->
+			<div data-testid="description-archive-folder">
+				<label for="archiveFolder" class="mb-1 block text-sm font-medium text-ink-2"
+					>Mappe
+					<FieldLabelBadge variant="replace" />
+				</label>
+				<input
+					id="archiveFolder"
+					type="text"
+					name="archiveFolder"
+					bind:value={archiveFolder}
+					class="block w-full rounded border border-line p-2 text-sm shadow-sm focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring"
+				/>
+			</div>
+		{/if}
 	</div>
 </div>