fix(journey): editor review round — labels, errors, pending state, a11y, tests

Addresses the remaining #792 review blockers and concerns in the journey
editor cluster:

- Interlude rows show 'Zwischentext' (dedicated key), not the add-button text
- All four mutation handlers route the backend ErrorCode through
  getErrorMessage (a 409 duplicate no longer says 'bitte Seite neu laden')
  and console.error their failures so client-side errors leave a trace
- Remove implements the spec'd pending state: row stays dimmed with an
  aria-live 'wird entfernt…' until the DELETE resolves; failure keeps the row
- Move announcements fire after the reorder resolves (no false 'verschoben')
- Touch targets ≥44px (remove ×, note links, create submit); focus moves to
  the new row after add, to a sensible neighbor after remove, back to × on
  confirm-cancel; drag handle is pointer-only; title/intro get aria-labels;
  publish-disabled reason is a visible hint, not a title tooltip
- Amber warning styles use new --color-warning-* tokens with dark remaps
- Blocked interlude-clear restores the draft instead of showing phantom text
- useBlockDragDrop moves to $lib/shared/hooks — geschichte no longer imports
  another domain's internals
- Test hardening: reorder-failure rollback (non-ok + reject), publish/
  unpublish/empty-warning surface, destructive confirm path, maxlength
  assertions, JourneyCreate failure path, edit-page STORY/JOURNEY branch,
  fixture factory, m.* assertions, all fixed sleeps replaced with polling

67 component tests green across 6 spec files; transcription consumer of the
moved hook re-verified (30 green).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/routes/geschichten/new/JourneyCreate.svelte

@@ -60,6 +60,7 @@ async function handleSubmit(e: SubmitEvent) {
 			bind:value={title}
 			onblur={() => (titleTouched = true)}
 			placeholder={m.geschichte_editor_title_placeholder()}
+			aria-label={m.journey_title_aria_label()}
 			aria-invalid={showTitleError}
 			class="block w-full rounded border px-3 py-2 font-serif text-lg text-ink placeholder:text-ink-3 focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring {showTitleError
 				? 'border-danger'
@@ -74,7 +75,7 @@ async function handleSubmit(e: SubmitEvent) {
 		<button
 			type="submit"
 			disabled={submitting}
-			class="rounded bg-brand-navy px-4 py-2 font-sans text-sm font-medium text-white hover:opacity-90 focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring disabled:opacity-50"
+			class="inline-flex h-11 items-center rounded bg-brand-navy px-4 font-sans text-sm font-medium text-white hover:opacity-90 focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring disabled:opacity-50"
 		>
 			{m.journey_create_submit()}
 		</button>

frontend/src/routes/geschichten/new/JourneyCreate.svelte.spec.ts

@@ -0,0 +1,73 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page, userEvent } from 'vitest/browser';
+import { m } from '$lib/paraglide/messages.js';
+import { getErrorMessage } from '$lib/shared/errors';
+
+vi.mock('$app/navigation', () => ({
+	goto: vi.fn()
+}));
+
+const { default: JourneyCreate } = await import('./JourneyCreate.svelte');
+
+afterEach(() => {
+	cleanup();
+	vi.unstubAllGlobals();
+});
+
+describe('JourneyCreate — failure path', () => {
+	it('renders the mapped error message when POST /api/geschichten fails with a code', async () => {
+		vi.stubGlobal(
+			'fetch',
+			vi.fn().mockResolvedValue({
+				ok: false,
+				json: vi.fn().mockResolvedValue({ code: 'VALIDATION_ERROR' })
+			})
+		);
+
+		render(JourneyCreate, {});
+
+		await userEvent.fill(
+			page.getByRole('textbox', { name: m.journey_title_aria_label() }),
+			'Meine Lesereise'
+		);
+		await userEvent.click(page.getByRole('button', { name: m.journey_create_submit() }));
+
+		const alert = page.getByRole('alert');
+		await expect.element(alert).toBeInTheDocument();
+		await expect.element(alert).toHaveTextContent(getErrorMessage('VALIDATION_ERROR'));
+	});
+
+	it('navigates to the edit page on success', async () => {
+		const { goto } = await import('$app/navigation');
+		vi.mocked(goto).mockClear();
+		vi.stubGlobal(
+			'fetch',
+			vi.fn().mockResolvedValue({
+				ok: true,
+				json: vi.fn().mockResolvedValue({ id: 'g-new' })
+			})
+		);
+
+		render(JourneyCreate, {});
+
+		await userEvent.fill(
+			page.getByRole('textbox', { name: m.journey_title_aria_label() }),
+			'Meine Lesereise'
+		);
+		await userEvent.click(page.getByRole('button', { name: m.journey_create_submit() }));
+
+		await vi.waitFor(() => {
+			expect(goto).toHaveBeenCalledWith('/geschichten/g-new/edit');
+		});
+	});
+
+	it('has an accessible label on the title input', async () => {
+		vi.stubGlobal('fetch', vi.fn());
+		render(JourneyCreate, {});
+
+		await expect
+			.element(page.getByRole('textbox', { name: m.journey_title_aria_label() }))
+			.toBeInTheDocument();
+	});
+});