merge(frontend): resolve conflicts with main — integrate fileHash feature into panel architecture

Keep the new bottom-panel / AnnotationSidePanel architecture from this branch
while pulling in the documentFileHash / visibleAnnotations filter that was added
on main. Thread documentFileHash through DocumentViewer so outdated-annotation
filtering works end-to-end.

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

frontend/src/lib/components/DocumentViewer.svelte

@@ -6,6 +6,7 @@ type Doc = {
 	id: string;
 	filePath?: string | null;
 	contentType?: string | null;
+	fileHash?: string | null;
 };
 
 type Props = {
@@ -83,6 +84,7 @@ let {
 			bind:activeAnnotationId={activeAnnotationId}
 			bind:activeAnnotationPage={activeAnnotationPage}
 			onAnnotationClick={onAnnotationClick}
+			documentFileHash={doc.fileHash ?? null}
 		/>
 	{:else if fileUrl}
 		<div class="flex h-full w-full items-center justify-center overflow-auto p-8">

frontend/src/lib/components/PdfViewer.svelte

@@ -11,7 +11,8 @@ let {
 	annotateMode = $bindable(false),
 	activeAnnotationId = $bindable<string | null>(null),
 	activeAnnotationPage = $bindable<number | null>(null),
-	onAnnotationClick
+	onAnnotationClick,
+	documentFileHash
 }: {
 	url: string;
 	documentId?: string;
@@ -19,6 +20,7 @@ let {
 	activeAnnotationId?: string | null;
 	activeAnnotationPage?: number | null;
 	onAnnotationClick?: (id: string) => void;
+	documentFileHash?: string | null;
 } = $props();
 
 let pdfDoc = $state<PDFDocumentProxy | null>(null);
@@ -51,6 +53,7 @@ type Annotation = {
 	height: number;
 	color: string;
 	createdAt: string;
+	fileHash?: string | null;
 };
 
 let annotations = $state<Annotation[]>([]);
@@ -58,6 +61,11 @@ let annotateColor = $state('#ffff00');
 let commentCounts = new SvelteMap<string, number>();
 let showAnnotations = $state(true);
 
+const visibleAnnotations = $derived(
+	annotations.filter((a) => !a.fileHash || !documentFileHash || a.fileHash === documentFileHash)
+);
+const outdatedCount = $derived(annotations.length - visibleAnnotations.length);
+
 onMount(async () => {
 	// Dynamic import keeps pdfjs out of the SSR bundle entirely
 	const [lib, { default: workerUrl }] = await Promise.all([
@@ -306,6 +314,27 @@ function zoomOut() {
 	</div>
 {:else}
 	<div class="flex h-full w-full flex-col bg-[#2A2A2A]">
+		{#if outdatedCount > 0}
+			<div
+				class="flex shrink-0 items-center gap-2 border-b border-amber-500/30 bg-amber-500/10 px-4 py-2"
+				data-testid="annotation-outdated-notice"
+			>
+				<svg
+					class="h-4 w-4 shrink-0 text-amber-400"
+					viewBox="0 0 24 24"
+					fill="none"
+					stroke="currentColor"
+					stroke-width="2"
+				>
+					<path
+						stroke-linecap="round"
+						stroke-linejoin="round"
+						d="M12 9v3.75m-9.303 3.376c-.866 1.5.217 3.374 1.948 3.374h14.71c1.73 0 2.813-1.874 1.948-3.374L13.949 3.378c-.866-1.5-3.032-1.5-3.898 0L2.697 16.126zM12 15.75h.007v.008H12v-.008z"
+					/>
+				</svg>
+				<span class="font-sans text-xs text-amber-300">{m.annotation_outdated_notice()}</span>
+			</div>
+		{/if}
 		<!-- Controls -->
 		<div
 			class="flex shrink-0 items-center justify-between gap-2 border-b border-white/10 px-4 py-2"
@@ -466,7 +495,7 @@ function zoomOut() {
 						></div>
 						{#if showAnnotations}
 							<AnnotationLayer
-								annotations={annotations.filter((a) => a.pageNumber === currentPage)}
+								annotations={visibleAnnotations.filter((a) => a.pageNumber === currentPage)}
 								canAnnotate={annotateMode}
 								color={annotateColor}
 								onDraw={handleAnnotationDraw}