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

@@ -0,0 +1,40 @@
+<script lang="ts">
+import { m } from '$lib/paraglide/messages.js';
+
+let {
+	variant,
+	count = 0,
+	children
+}: {
+	variant: 'per-file' | 'shared';
+	count?: number;
+	children?: import('svelte').Snippet;
+} = $props();
+</script>
+
+<div
+	data-testid="scope-card"
+	data-variant={variant}
+	class="mb-3 rounded-sm border p-4
+		{variant === 'per-file'
+		? 'border-accent bg-accent-bg'
+		: 'border-line bg-surface'}"
+>
+	{#if variant === 'shared'}
+		<div class="mb-3 flex items-center justify-between">
+			<span class="text-xs font-bold tracking-widest text-ink-3 uppercase">
+				{m.bulk_scope_shared_label({ count })}
+			</span>
+			<span
+				class="inline-flex h-5 min-w-5 items-center justify-center rounded-full bg-accent px-1.5 text-xs font-bold text-primary"
+			>
+				{count}
+			</span>
+		</div>
+	{:else}
+		<p class="mb-3 text-xs font-bold tracking-widest text-primary uppercase">
+			{m.bulk_scope_per_file_label()}
+		</p>
+	{/if}
+	{@render children?.()}
+</div>