Fix rubocop linting issues in API chat endpoints

- Fix trailing whitespace
- Add missing final newlines
- Fix array bracket spacing
- Auto-corrected all layout issues

🤖 Generated with [Claude Code](https://claude.ai/code)

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

app/views/api/v1/chats/show.json.jbuilder

@@ -10,7 +10,7 @@ json.messages @messages do |message|
   json.model message.ai_model if message.type == "AssistantMessage"
   json.created_at message.created_at.iso8601
   json.updated_at message.updated_at.iso8601
-  
+
   # Include tool calls for assistant messages
   if message.type == "AssistantMessage" && message.tool_calls.any?
     json.tool_calls message.tool_calls do |tool_call|
@@ -30,4 +30,4 @@ if @pagy
     json.total_count @pagy.count
     json.total_pages @pagy.pages
   end
-end
+end