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/TranscriptionEditView.svelte

@@ -30,34 +30,9 @@ let activeBlockId: string | null = $state(null);
 let saveStates = new SvelteMap<string, SaveState>();
 let debounceTimers = new SvelteMap<string, ReturnType<typeof setTimeout>>();
 let pendingTexts = new SvelteMap<string, string>();
-let commentCounts = new SvelteMap<string, number>();
-
 let sortedBlocks = $derived([...blocks].sort((a, b) => a.sortOrder - b.sortOrder));
 let hasBlocks = $derived(blocks.length > 0);
 
-async function loadCommentCounts() {
-	for (const block of blocks) {
-		try {
-			const res = await fetch(
-				`/api/documents/${documentId}/transcription-blocks/${block.id}/comments`
-			);
-			if (res.ok) {
-				const comments = (await res.json()) as Array<{ replies: unknown[] }>;
-				const total = comments.reduce((s, c) => s + 1 + (c.replies?.length ?? 0), 0);
-				commentCounts.set(block.id, total);
-			}
-		} catch {
-			// ignore
-		}
-	}
-}
-
-$effect(() => {
-	if (blocks.length > 0) {
-		loadCommentCounts();
-	}
-});
-
 function getSaveState(blockId: string): SaveState {
 	return saveStates.get(blockId) ?? 'idle';
 }
@@ -191,7 +166,6 @@ $effect(() => {
 						saveState={getSaveState(block.id)}
 						canComment={canComment}
 						currentUserId={currentUserId}
-						commentCount={commentCounts.get(block.id) ?? 0}
 						onTextChange={(text) => handleTextChange(block.id, text)}
 						onFocus={() => handleFocus(block.id)}
 						onDeleteClick={() => handleDelete(block.id)}