Display tool calls in message template (#416)

## Summary
- Added visualization of tool calls in the chat UI message partial
- Tool calls are displayed with function name and arguments in JSON
format
- Styled with monospace font and gray background for better readability

## Test plan
- [ ] Generate a chat UI with the updated template
- [ ] Verify tool calls are displayed correctly in messages
- [ ] Check that messages without tool calls render normally

<img width="730" height="554" alt="CleanShot 2025-09-21 at 22 21 23@2x"
src="https://github.com/user-attachments/assets/058c0923-4081-4399-96c0-4a4e025f7244"
/>

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

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: marckohlbrugge

lib/generators/ruby_llm/chat_ui/chat_ui_generator.rb

@@ -33,7 +33,7 @@ def parse_model_mappings
         @model_names
       end
 
-      %i[chat message model].each do |type|
+      %i[chat message model tool_call].each do |type|
         define_method("#{type}_model_name") do
           @model_names ||= parse_model_mappings
           @model_names[type]
@@ -56,6 +56,8 @@ def create_views
         # Message views
         template 'views/messages/_message.html.erb',
                  "app/views/#{message_table_name}/_#{message_model_name.underscore}.html.erb"
+        template 'views/messages/_tool_calls.html.erb',
+                 "app/views/#{message_table_name}/_#{tool_call_model_name.tableize}.html.erb"
         template 'views/messages/_content.html.erb', "app/views/#{message_table_name}/_content.html.erb"
         template 'views/messages/_form.html.erb', "app/views/#{message_table_name}/_form.html.erb"
         template 'views/messages/create.turbo_stream.erb',

lib/generators/ruby_llm/chat_ui/templates/views/messages/_message.html.erb.tt

@@ -4,6 +4,9 @@
     <%%= <%= message_model_name.underscore %>.role&.capitalize %>
   </div>
   <div id="<%%= dom_id(<%= message_model_name.underscore %>) %>_content" style="white-space: pre-wrap;"><%%= <%= message_model_name.underscore %>.content %></div>
+  <%% if <%= message_model_name.underscore %>.<%= tool_call_model_name.tableize %>.any? %>
+    <%%= render "<%= message_table_name %>/<%= tool_call_model_name.tableize %>", <%= message_model_name.underscore %>: <%= message_model_name.underscore %> %>
+  <%% end %>
   <div style="font-size: 0.85em; color: #666; margin-top: 5px;">
     <%%= <%= message_model_name.underscore %>.created_at&.strftime("%I:%M %p") %>
   </div>

lib/generators/ruby_llm/chat_ui/templates/views/messages/_tool_calls.html.erb.tt

@@ -0,0 +1,7 @@
+<div style="display: flex; flex-direction: column; gap: 3px; align-items: flex-start; font-family: monospace;">
+  <%% <%= message_model_name.underscore %>.tool_calls.each do |tool_call| %>
+    <div style="background: #eee; padding: 5px; border-radius: 4px;">
+      <%%= tool_call.name %>(<%%= tool_call.arguments.map { |k, v| "#{k}: #{v.inspect}" }.join(", ") %>)
+    </div>
+  <%% end %>
+</div>