fix(transcription): always show comment list, compose box on demand

Comments were only visible after clicking "Kommentieren". Now:
- Comment list always renders (CommentThread with loadOnMount=true)
- Compose box hidden by default (showCompose prop on CommentThread)
- Clicking "Kommentieren" sets commentOpen=true → shows compose box
- Closing hides compose box but comments remain visible

This separates "viewing comments" (always) from "writing a comment"
(on demand via Kommentieren button).

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

frontend/src/lib/components/TranscriptionBlock.svelte

@@ -14,7 +14,6 @@ type Props = {
 	saveState: SaveState;
 	canComment: boolean;
 	currentUserId: string | null;
-	commentCount: number;
 	onTextChange: (text: string) => void;
 	onFocus: () => void;
 	onDeleteClick: () => void;
@@ -31,7 +30,6 @@ let {
 	saveState,
 	canComment,
 	currentUserId,
-	commentCount,
 	onTextChange,
 	onFocus,
 	onDeleteClick,
@@ -39,7 +37,7 @@ let {
 }: Props = $props();
 
 let localText = $state(text);
-let commentOpen = $state(commentCount > 0);
+let commentOpen = $state(false);
 let selectedQuote = $state<string | null>(null);
 let textareaEl = $state<HTMLTextAreaElement | null>(null);
 
@@ -199,34 +197,18 @@ function captureSelectionAndOpenComments() {
 			</div>
 		</div>
 
-		<!-- Comment thread (expandable) -->
-		{#if commentOpen}
-			<div class="mt-3 border-t border-line pt-3">
-				<div class="mb-2 flex items-center justify-between">
-					<span class="font-sans text-xs font-semibold text-ink-2">
-						{m.comment_section_title()}
-					</span>
-					<button
-						type="button"
-						class="font-sans text-xs text-ink-3 transition-colors hover:text-ink"
-						onclick={() => {
-							commentOpen = false;
-							selectedQuote = null;
-						}}
-					>
-						{m.comment_panel_close()}
-					</button>
-				</div>
-				<CommentThread
-					documentId={documentId}
-					blockId={blockId}
-					loadOnMount={true}
-					canComment={canComment}
-					currentUserId={currentUserId}
-					canAdmin={false}
-					quotedText={selectedQuote}
-				/>
-			</div>
-		{/if}
+		<!-- Comment thread — list always visible, compose toggled by Kommentieren -->
+		<div class="mt-3 border-t border-line pt-3">
+			<CommentThread
+				documentId={documentId}
+				blockId={blockId}
+				loadOnMount={true}
+				canComment={canComment}
+				currentUserId={currentUserId}
+				canAdmin={false}
+				quotedText={selectedQuote}
+				showCompose={commentOpen}
+			/>
+		</div>
 	</div>
 </div>