feat(frontend): keep annotation tab after switching to document discussion

Clicking the Diskussion sub-tab no longer deselects the active annotation,
so the Annotation tab stays visible and accessible for easy toggling back.

The annotation is cleared only via Escape or clicking elsewhere on the PDF.
Removes the now-unused onClearAnnotation callback chain.

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

frontend/src/lib/components/DocumentBottomPanel.svelte

@@ -50,7 +50,6 @@ type Props = {
 	activeTab: Tab;
 	activeAnnotationId: string | null;
 	activeAnnotationPage: number | null;
-	onClearAnnotation?: () => void;
 	onAnnotationCommentCountChange?: (annotationId: string, count: number) => void;
 };
 
@@ -65,7 +64,6 @@ let {
 	activeTab = $bindable(),
 	activeAnnotationId,
 	activeAnnotationPage,
-	onClearAnnotation,
 	onAnnotationCommentCountChange
 }: Props = $props();
 
@@ -191,7 +189,6 @@ const panelHeight = $derived(open ? height : MIN_HEIGHT);
 					canComment={canComment}
 					currentUserId={currentUserId}
 					canAdmin={canAdmin}
-					onClearAnnotation={onClearAnnotation}
 					onAnnotationCommentCountChange={onAnnotationCommentCountChange}
 				/>
 			{:else if activeTab === 'history'}

frontend/src/lib/components/PanelDiscussion.svelte

@@ -29,7 +29,6 @@ type Props = {
 	canComment: boolean;
 	currentUserId: string | null;
 	canAdmin: boolean;
-	onClearAnnotation?: () => void;
 	onAnnotationCommentCountChange?: (annotationId: string, count: number) => void;
 };
 
@@ -41,7 +40,6 @@ let {
 	canComment,
 	currentUserId,
 	canAdmin,
-	onClearAnnotation,
 	onAnnotationCommentCountChange
 }: Props = $props();
 
@@ -64,7 +62,6 @@ $effect(() => {
 
 function selectDocumentTab() {
 	activeSubTab = 'document';
-	onClearAnnotation?.();
 }
 
 function selectAnnotationTab() {

frontend/src/routes/documents/[id]/+page.svelte

@@ -162,8 +162,4 @@ $effect(() => {
 	bind:activeTab={activeTab}
 	activeAnnotationId={activeAnnotationId}
 	activeAnnotationPage={activeAnnotationPage}
-	onClearAnnotation={() => {
-		activeAnnotationId = null;
-		activeAnnotationPage = null;
-	}}
 />