v0.0.3: add built-in web tools

Add no-key web_search and web_fetch tools.
Fetch pages with net/http and parse HTML content.
Document built-in web capabilities.

cmd/agentu/main.go

@@ -60,6 +60,8 @@ func run() error {
 	} else {
 		registry = tools.ReadOnlyBuiltins(cfg.Agent.WorkingDir)
 	}
+	registry.Register(tools.NewBuiltinSearchTool(http.DefaultClient))
+	registry.Register(tools.NewBuiltinFetchTool(http.DefaultClient))
 	systemPrompt := strings.TrimSpace(cfg.Agent.SystemPrompt + "\n\n" + tools.AgentInstructions(cfg.Agent.WorkingDir, *yolo))
 
 	assistant := agent.New(agent.Options{