Fix comment tree display (Issue #10)

- Add build_comment_tree() to organize comments hierarchically
- Create recursive Jinja macro to render nested comments
- Add visual styling with left border and indentation
- Comments now display as threaded tree structure

Fixes #10

app.py

@@ -575,35 +575,62 @@ def api_content_timestamp():
         return jsonify({'error': 'Failed to get content timestamp'}), 500
 
 
+def build_comment_tree(comments):
+    """Build a hierarchical comment tree from flat comment list"""
+    # Create lookup dict by UUID
+    comment_dict = {c['uuid']: {**c, 'replies': []} for c in comments}
+
+    # Build tree structure
+    root_comments = []
+    for comment in comments:
+        parent_uuid = comment.get('parent_comment_uuid')
+        if parent_uuid and parent_uuid in comment_dict:
+            # Add as reply to parent
+            comment_dict[parent_uuid]['replies'].append(comment_dict[comment['uuid']])
+        else:
+            # Top-level comment
+            root_comments.append(comment_dict[comment['uuid']])
+
+    # Sort at each level by timestamp
+    def sort_tree(comments_list):
+        comments_list.sort(key=lambda x: x.get('timestamp', 0))
+        for comment in comments_list:
+            if comment.get('replies'):
+                sort_tree(comment['replies'])
+
+    sort_tree(root_comments)
+    return root_comments
+
+
 @app.route('/post/<post_id>')
 def post_detail(post_id):
     """Serve individual post detail page with modern theme"""
     try:
         # Load platform configuration
         platform_config = load_platform_config()
-        
+
         # Use cached data for better performance
         cached_posts, cached_comments = _load_posts_cache()
-        
+
         # Get post data from cache
         post_data = cached_posts.get(post_id)
         if not post_data:
             return render_template('404.html'), 404
-            
+
         # Add source display name
         post_data['source_display'] = get_display_name_for_source(
             post_data.get('platform', ''),
             post_data.get('source', ''),
             platform_config
         )
-            
-        # Get comments from cache
-        comments = cached_comments.get(post_id, [])
-        logger.info(f"Loading post {post_id}: found {len(comments)} comments")
 
-        # Sort comments by timestamp
-        comments.sort(key=lambda x: x.get('timestamp', 0))
-        
+        # Get comments from cache
+        comments_flat = cached_comments.get(post_id, [])
+        logger.info(f"Loading post {post_id}: found {len(comments_flat)} comments")
+
+        # Build comment tree
+        comments = build_comment_tree(comments_flat)
+
         # Load user settings if authenticated
         user_settings = {}
         if current_user.is_authenticated:
@@ -611,9 +638,9 @@ def post_detail(post_id):
                 user_settings = json.loads(current_user.settings) if current_user.settings else {}
             except:
                 user_settings = {}
-        
+
         return render_template('post_detail.html', post=post_data, comments=comments, user_settings=user_settings)
-        
+
     except Exception as e:
         print(f"Error loading post {post_id}: {e}")
         return render_template('404.html'), 404