feat(comment): tighten the comments panel density

The Comments panel was sparse: 12px inner/outer paddings per thread, a
16px gap between avatar and body, body text at the global 16px ProseMirror
size. On a narrow aside column this ate vertical space - few comments per
screen, lots of air.

Tighten strictly inside features/comment (the shared aside frame is left
untouched, so TOC/Details tabs keep their padding):

- Thread Paper: p='sm'->p='xs', mb='sm'->mb='xs' (12->10px).
- Reply-editor Divider: my={4}->my={2}.
- CommentListItem outer Box: pb='xs'->pb={6}; the header Group
  (avatar + body) gains gap='xs' (16->10px).
- Font hierarchy: author name sm->xs (14->12px, fw=500 kept), selection
  quote sm->xs; comment body via a scoped CSS override on
  .commentEditor .ProseMirror: font-size sm (14px) + line-height 1.4,
  margin-top 10->4. The page editor is unaffected (the override is
  scoped to the comment editor module).
- Selection quote padding 8->6, margin-top 4->2.
- Dropped the unused .wrapper rule (no references).

apps/client/src/features/comment/components/comment-list-item.tsx

@@ -116,8 +116,8 @@ function CommentListItem({
   }
 
   return (
-    <Box ref={ref} pb="xs">
+    <Box ref={ref} pb={6}>
-      <Group>
+      <Group gap="xs">
         <CustomAvatar
           size="sm"
           avatarUrl={comment.creator.avatarUrl}
@@ -126,7 +126,7 @@ function CommentListItem({
 
         <div style={{ flex: 1 }}>
           <Group justify="space-between" wrap="nowrap">
-            <Text size="sm" fw={500} lineClamp={1}>
+            <Text size="xs" fw={500} lineClamp={1}>
               {comment.creator.name}
             </Text>
 
@@ -177,7 +177,7 @@ function CommentListItem({
             tabIndex={0}
             aria-label={t("Jump to comment selection")}
           >
-            <Text size="sm">{comment?.selection}</Text>
+            <Text size="xs">{comment?.selection}</Text>
           </Box>
         )}
 

apps/client/src/features/comment/components/comment-list-with-tabs.tsx

@@ -121,8 +121,8 @@ function CommentListWithTabs() {
       <Paper
         shadow="sm"
         radius="md"
-        p="sm"
+        p="xs"
-        mb="sm"
+        mb="xs"
         withBorder
         key={comment.id}
         data-comment-id={comment.id}
@@ -145,7 +145,7 @@ function CommentListWithTabs() {
 
         {!comment.resolvedAt && canComment && (
           <>
-            <Divider my={4} />
+            <Divider my={2} />
             <CommentEditorWithActions
               commentId={comment.id}
               onSave={handleAddReply}

apps/client/src/features/comment/components/comment.module.css

@@ -1,15 +1,11 @@
-.wrapper {
-    padding: var(--mantine-spacing-md);
-}
-
 .focused-thread {
     border: 2px solid #8d7249;
 }
 
 .textSelection {
-    margin-top: 4px;
+    margin-top: 2px;
     border-left: 2px solid var(--mantine-color-gray-6);
-    padding: 8px;
+    padding: 6px;
     background: var(--mantine-color-gray-light);
     cursor: pointer;
     overflow-wrap: break-word;
@@ -32,6 +28,9 @@
         box-shadow: 0 0 0 2px var(--mantine-color-blue-3);
     }
 
+    /* Denser comments: override the global 16px ProseMirror body size with 14px
+       and tighten the rhythm vs. the comment header. Scoped to the comment
+       editor only - the page editor is unaffected. */
     .ProseMirror :global(.ProseMirror){
         border-radius: var(--mantine-radius-sm);
         max-width: 100%;
@@ -39,7 +38,9 @@
         word-break: break-word;
         padding-left: 6px;
         padding-right: 6px;
-        margin-top: 10px;
+        font-size: var(--mantine-font-size-sm);
+        line-height: 1.4;
+        margin-top: 4px;
         margin-bottom: 2px;
     }