refactor: move document domain core to lib/document/

Moves ~25 components, utils (search, filename, groupDocuments,
documentStatusLabel, validateFile), bulkSelection store, and
TranscriptionSection sub-component. Fixes broken relative imports.

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

frontend/src/lib/document/WhoWhenSection.svelte.spec.ts

@@ -0,0 +1,42 @@
+import { afterEach, describe, expect, it } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page } from 'vitest/browser';
+import WhoWhenSection from './WhoWhenSection.svelte';
+
+afterEach(() => cleanup());
+
+describe('WhoWhenSection — onMount seeding (Felix B1 fix regression fence)', () => {
+	it('pre-fills the date input from initialDateIso when the bindable is empty', async () => {
+		render(WhoWhenSection, { initialDateIso: '2024-03-15' });
+		// isoToGerman('2024-03-15') → '15.03.2024'
+		const dateInput = document.querySelector('input#documentDate') as HTMLInputElement;
+		expect(dateInput).not.toBeNull();
+		expect(dateInput.value).toBe('15.03.2024');
+	});
+
+	it('does not stomp a parent-bound dateIso that is already non-empty', async () => {
+		// dateIso bindable is '2026-01-01' from the parent; initialDateIso is the
+		// "fallback seed". onMount must not overwrite the already-bound value.
+		render(WhoWhenSection, { dateIso: '2026-01-01', initialDateIso: '1900-01-01' });
+		const dateInput = document.querySelector('input#documentDate') as HTMLInputElement;
+		expect(dateInput.value).toBe('01.01.2026');
+	});
+
+	it('hides the date field when hideDate=true (bulk-edit mode)', async () => {
+		render(WhoWhenSection, { hideDate: true });
+		await expect.element(page.getByTestId('who-when-date')).not.toBeInTheDocument();
+	});
+
+	it('renders the meta_location input only outside editMode', async () => {
+		const { rerender } = render(WhoWhenSection, { editMode: true });
+		expect(document.querySelector('input#location')).toBeNull();
+		await rerender({ editMode: false });
+		expect(document.querySelector('input#location')).not.toBeNull();
+	});
+
+	it('pre-fills the location input from initialLocation', async () => {
+		render(WhoWhenSection, { editMode: false, initialLocation: 'Berlin' });
+		const locationInput = document.querySelector('input#location') as HTMLInputElement;
+		expect(locationInput.value).toBe('Berlin');
+	});
+});