feat(enrich): add metadata enrichment queue UI

Home page shows "Needs metadata" card when incomplete documents exist.
/enrich list shows all incomplete documents; /enrich/[id] provides a
split PDF-preview + compact form view with Skip / Save / Save & reviewed
actions that auto-advance through the queue.

New document page gets Save vs Save & reviewed split. Edit page gets
"Mark for review" secondary button to push a document back into the queue.

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

frontend/src/routes/documents/new/+page.svelte

@@ -62,12 +62,26 @@ let selectedReceivers: { id: string; firstName: string; lastName: string }[] = $
 			<a href="/" class="text-sm font-medium text-ink-2 transition-colors hover:text-ink">
 				{m.btn_cancel()}
 			</a>
-			<button
-				type="submit"
-				class="rounded bg-primary px-6 py-2 text-sm font-bold tracking-widest text-white uppercase transition-colors hover:bg-primary/80"
-			>
-				{m.btn_save()}
-			</button>
+			<div class="flex items-center gap-3">
+				<button
+					type="submit"
+					name="metadataComplete"
+					value="false"
+					formaction="?/save"
+					class="rounded-sm border border-gray-300 px-5 py-2 font-sans text-xs font-bold tracking-widest text-gray-600 uppercase transition-colors hover:bg-gray-50"
+				>
+					{m.btn_save()}
+				</button>
+				<button
+					type="submit"
+					name="metadataComplete"
+					value="true"
+					formaction="?/saveReviewed"
+					class="rounded-sm bg-brand-navy px-5 py-2 font-sans text-xs font-bold tracking-widest text-white uppercase transition-colors hover:bg-brand-navy/90"
+				>
+					{m.btn_save_and_mark_reviewed()}
+				</button>
+			</div>
 		</div>
 	</form>
 </div>