refactor: move shared utilities to lib/shared/ sub-packages

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

frontend/src/lib/shared/services/confirm.svelte.test.ts

@@ -0,0 +1,70 @@
+import { describe, it, expect, afterEach } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page, userEvent } from 'vitest/browser';
+import TestHost from './confirm.test-host.svelte';
+import type { ConfirmService } from './confirm.svelte.js';
+
+afterEach(cleanup);
+
+function makeHost(): { service: ConfirmService } {
+	const result: { service: ConfirmService | null } = { service: null };
+	render(TestHost, {
+		onReady: (s: ConfirmService) => {
+			result.service = s;
+		}
+	});
+	return result as { service: ConfirmService };
+}
+
+describe('ConfirmService', () => {
+	it('resolves true when the user clicks Confirm', async () => {
+		const { service } = makeHost();
+
+		const resultPromise = service.confirm({ title: 'Test?' });
+		await expect.element(page.getByRole('dialog')).toBeInTheDocument();
+		await page.getByRole('button', { name: 'Bestätigen' }).click();
+
+		expect(await resultPromise).toBe(true);
+	});
+
+	it('resolves false when the user clicks Cancel', async () => {
+		const { service } = makeHost();
+
+		const resultPromise = service.confirm({ title: 'Test?' });
+		await expect.element(page.getByRole('dialog')).toBeInTheDocument();
+		await page.getByRole('button', { name: 'Abbrechen' }).click();
+
+		expect(await resultPromise).toBe(false);
+	});
+
+	it('resolves false when Escape is pressed', async () => {
+		const { service } = makeHost();
+
+		const resultPromise = service.confirm({ title: 'Test?' });
+		await expect.element(page.getByRole('dialog')).toBeInTheDocument();
+		await userEvent.keyboard('{Escape}');
+
+		expect(await resultPromise).toBe(false);
+	});
+
+	it('resolves false immediately on a concurrent call while dialog is open', async () => {
+		const { service } = makeHost();
+
+		const first = service.confirm({ title: 'First?' });
+		await expect.element(page.getByRole('dialog')).toBeInTheDocument();
+
+		const second = service.confirm({ title: 'Second?' });
+		expect(await second).toBe(false);
+
+		// clean up the first dialog
+		await page.getByRole('button', { name: 'Abbrechen' }).click();
+		expect(await first).toBe(false);
+	});
+
+	it('throws a descriptive error when called outside provider tree', async () => {
+		const { getConfirmService } = await import('./confirm.svelte.js');
+		// Outside component init, getContext throws or returns undefined — our guard
+		// converts either case to a descriptive developer error
+		expect(() => getConfirmService()).toThrow('mount <ConfirmDialog>');
+	});
+});