feat(journey-editor): build JourneyAddBar with document picker and interlude draft

Two add buttons: document picker (DocumentPickerDropdown) and interlude inline
draft form. Interlude confirm is aria-disabled until text is non-empty. Closing
one panel opens the other. Tests cover all three plan test cases.

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

frontend/src/lib/geschichte/JourneyAddBar.svelte.spec.ts

@@ -0,0 +1,53 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page, userEvent } from 'vitest/browser';
+import JourneyAddBar from './JourneyAddBar.svelte';
+
+afterEach(() => cleanup());
+
+describe('JourneyAddBar — interlude flow', () => {
+	it('interlude confirm button is aria-disabled until text is non-empty', async () => {
+		render(JourneyAddBar, { onAddDocument: vi.fn(), onAddInterlude: vi.fn() });
+
+		await userEvent.click(page.getByText('Zwischentext hinzufügen'));
+
+		const confirmBtn = page.getByRole('button', { name: 'Hinzufügen' });
+		await expect.element(confirmBtn).toHaveAttribute('aria-disabled', 'true');
+	});
+
+	it('confirm becomes active after typing text', async () => {
+		render(JourneyAddBar, { onAddDocument: vi.fn(), onAddInterlude: vi.fn() });
+
+		await userEvent.click(page.getByText('Zwischentext hinzufügen'));
+		await userEvent.fill(page.getByRole('textbox'), 'Eine schöne Reise');
+
+		const confirmBtn = page.getByRole('button', { name: 'Hinzufügen' });
+		await expect.element(confirmBtn).toHaveAttribute('aria-disabled', 'false');
+	});
+
+	it('calls onAddInterlude with text on confirm', async () => {
+		const onAddInterlude = vi.fn();
+		render(JourneyAddBar, { onAddDocument: vi.fn(), onAddInterlude });
+
+		await userEvent.click(page.getByText('Zwischentext hinzufügen'));
+		await userEvent.fill(page.getByRole('textbox'), 'Reise nach Wien');
+		await userEvent.click(page.getByRole('button', { name: 'Hinzufügen' }));
+
+		expect(onAddInterlude).toHaveBeenCalledWith('Reise nach Wien');
+	});
+});
+
+describe('JourneyAddBar — document picker', () => {
+	it('reveals picker when "Brief hinzufügen" is clicked', async () => {
+		vi.stubGlobal(
+			'fetch',
+			vi.fn().mockResolvedValue({ ok: true, json: vi.fn().mockResolvedValue({ items: [] }) })
+		);
+		render(JourneyAddBar, { onAddDocument: vi.fn(), onAddInterlude: vi.fn() });
+
+		await userEvent.click(page.getByText('Brief hinzufügen'));
+
+		await expect.element(page.getByRole('combobox')).toBeInTheDocument();
+		vi.unstubAllGlobals();
+	});
+});