webui: add diff display for patches

Co-Authored-By: sketch <hello@sketch.dev>
Change-ID: s2e9bdfb014ddec3ck
diff --git a/loop/agent.go b/loop/agent.go
index c98e7f7..cf35eb4 100644
--- a/loop/agent.go
+++ b/loop/agent.go
@@ -224,6 +224,9 @@
 	// TodoContent contains the agent's todo file content when it has changed
 	TodoContent *string `json:"todo_content,omitempty"`
 
+	// Display contains content to be displayed to the user, set by tools
+	Display any `json:"display,omitempty"`
+
 	Idx int `json:"idx"`
 }
 
@@ -905,6 +908,7 @@
 		ToolCallId: content.ToolUseID,
 		StartTime:  content.ToolUseStartTime,
 		EndTime:    content.ToolUseEndTime,
+		Display:    content.Display,
 	}
 
 	// Calculate the elapsed time if both start and end times are set