feat: sistema de prompts externos y mejoras en runtime de agentes

Añade pkg/command/prompts.go para cargar prompts desde archivos .md externos
en el directorio prompts/. Mejoras en agents/runtime.go para el manejo de
herramientas y flujo de ejecución. Nuevos comandos en agents/commands.go.
Ajustes menores en pkg/command/builtins.go para integrar las nuevas capacidades.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pkg/command/builtins.go

@@ -39,6 +39,11 @@ func Builtins() []Spec {
 			Description: "Limpia ventana de conversacion del room actual",
 			Usage:       "!clear",
 		},
+		{
+			Name:        "prompts",
+			Description: "Lista prompt-commands disponibles (archivos .md en prompts/)",
+			Usage:       "!prompts",
+		},
 		{
 			Name:        "version",
 			Aliases:     []string{"v"},

pkg/command/prompts.go

@@ -0,0 +1,51 @@
+package command
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// PromptCommand maps a command name to its prompt content loaded from a .md file.
+type PromptCommand struct {
+	Name    string // filename without .md extension
+	Content string // file content (the prompt text)
+}
+
+// LoadPromptCommands scans dir for .md files and returns one PromptCommand per file.
+// Returns nil (no error) if the directory does not exist.
+func LoadPromptCommands(dir string) ([]PromptCommand, error) {
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, nil
+		}
+		return nil, err
+	}
+
+	var prompts []PromptCommand
+	for _, e := range entries {
+		if e.IsDir() || !strings.HasSuffix(e.Name(), ".md") {
+			continue
+		}
+		data, err := os.ReadFile(filepath.Join(dir, e.Name()))
+		if err != nil {
+			continue
+		}
+		name := strings.TrimSuffix(e.Name(), ".md")
+		prompts = append(prompts, PromptCommand{
+			Name:    name,
+			Content: strings.TrimSpace(string(data)),
+		})
+	}
+	return prompts, nil
+}
+
+// ExpandPrompt builds the final message by concatenating the prompt content
+// with any extra arguments the user provided after the command.
+func ExpandPrompt(content string, args []string) string {
+	if len(args) == 0 {
+		return content
+	}
+	return content + "\n\n" + strings.Join(args, " ")
+}