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/ScopeCard.svelte.spec.ts

@@ -0,0 +1,32 @@
+import { describe, it, expect, afterEach } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page } from 'vitest/browser';
+import ScopeCard from './ScopeCard.svelte';
+
+afterEach(cleanup);
+
+describe('ScopeCard', () => {
+	it('per-file variant has accent background class', async () => {
+		const { container } = render(ScopeCard, { variant: 'per-file', count: 1 });
+		const card = container.querySelector('[data-testid="scope-card"]');
+		expect(card?.className).toMatch(/bg-accent-bg/);
+	});
+
+	it('shared variant does not have accent background', async () => {
+		const { container } = render(ScopeCard, { variant: 'shared', count: 3 });
+		const card = container.querySelector('[data-testid="scope-card"]');
+		expect(card?.className).not.toMatch(/bg-accent-bg/);
+	});
+
+	it('shared variant renders count badge with file count', async () => {
+		render(ScopeCard, { variant: 'shared', count: 5 });
+		await expect.element(page.getByText('5', { exact: true })).toBeInTheDocument();
+	});
+
+	it('per-file variant renders slot content', async () => {
+		// ScopeCard is a container — verify it renders children
+		render(ScopeCard, { variant: 'per-file', count: 1 });
+		const card = await page.getByTestId('scope-card');
+		await expect.element(card).toBeInTheDocument();
+	});
+});