feat: controles de hot-reload por agente en el dashboard TUI

Añade opciones de Reload (hot-reload) separadas de Restart (reinicio
completo) en el dashboard, usando el mecanismo SIGHUP implementado en
el issue 0013.

Cambios en pkg/tui/ (capa pura):
- IntentReloadAgent: hot-reload de un agente individual via SIGHUP
- IntentReloadAll: hot-reload de todos los agentes via SIGHUP
- AgentActionOptions: añade "Reload" antes de "Restart" con descripciones
  clarificadas ("sin interrumpir los demás" vs "launcher completo")
- ServerMenuOptions (running): añade "Reload All" como primera opción
- executeAction: maneja "Reload" → IntentReloadAgent
- executeServerAction: maneja "Reload All" → IntentReloadAll
- Mensajes de estado diferenciados: "Reload OK — X recargado sin
  interrupciones" vs "Restart OK — launcher reiniciado"

Cambios en shell/tui/ (capa impura):
- reloadAgent(id): escribe run/reload.txt + SIGHUP; error si launcher
  no está corriendo (no hay fallback a full restart)
- reloadAll(): elimina reload.txt + SIGHUP; error si no está corriendo
- restartAgent(id): restaurado a su comportamiento original de
  stop+start completo del launcher

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

shell/tui/adapter.go

@@ -39,6 +39,12 @@ func (a *Adapter) RunIntent(intent puretui.Intent) tea.Cmd {
 	case puretui.IntentDisableAgent:
 		return a.disableAgent(intent.AgentID)
 
+	case puretui.IntentReloadAgent:
+		return a.reloadAgent(intent.AgentID)
+
+	case puretui.IntentReloadAll:
+		return a.reloadAll()
+
 	case puretui.IntentRestartAgent:
 		return a.restartAgent(intent.AgentID)
 
@@ -140,30 +146,57 @@ func (a *Adapter) disableAgent(id string) tea.Cmd {
 	}
 }
 
-func (a *Adapter) restartAgent(id string) tea.Cmd {
+// reloadAgent hot-reloads a single agent via SIGHUP without stopping the launcher.
+func (a *Adapter) reloadAgent(id string) tea.Cmd {
 	return func() tea.Msg {
 		pid := a.mgr.UnifiedPID()
 		if pid <= 0 {
-			// Launcher not running — fall back to full restart.
-			_ = a.mgr.StopUnified()
-			time.Sleep(500 * time.Millisecond)
-			err := a.mgr.StartUnified()
-			if err == nil {
-				time.Sleep(500 * time.Millisecond)
-			}
-			return puretui.MsgActionDone{AgentID: id, Action: "Restart", Err: err}
+			return puretui.MsgActionDone{AgentID: id, Action: "Reload",
+				Err: fmt.Errorf("el launcher no está corriendo")}
 		}
-
-		// Launcher is running — write target and send SIGHUP for hot-reload.
 		if id != "" {
-			_ = os.WriteFile("run/reload.txt", []byte(id), 0o644)
+			if err := os.WriteFile("run/reload.txt", []byte(id), 0o644); err != nil {
+				return puretui.MsgActionDone{AgentID: id, Action: "Reload", Err: err}
+			}
 		}
 		err := syscall.Kill(pid, syscall.SIGHUP)
 		if err != nil {
-			return puretui.MsgActionDone{AgentID: id, Action: "Restart", Err: err}
+			return puretui.MsgActionDone{AgentID: id, Action: "Reload", Err: err}
 		}
 		time.Sleep(1 * time.Second)
-		return puretui.MsgActionDone{AgentID: id, Action: "Restart", Err: nil}
+		return puretui.MsgActionDone{AgentID: id, Action: "Reload", Err: nil}
+	}
+}
+
+// reloadAll hot-reloads all agents via SIGHUP (no reload.txt → reload all).
+func (a *Adapter) reloadAll() tea.Cmd {
+	return func() tea.Msg {
+		pid := a.mgr.UnifiedPID()
+		if pid <= 0 {
+			return puretui.MsgServerActionDone{Action: "Reload All",
+				Err: fmt.Errorf("el launcher no está corriendo")}
+		}
+		// Remove stale reload.txt so the launcher reloads all agents.
+		_ = os.Remove("run/reload.txt")
+		err := syscall.Kill(pid, syscall.SIGHUP)
+		if err != nil {
+			return puretui.MsgServerActionDone{Action: "Reload All", Err: err}
+		}
+		time.Sleep(1 * time.Second)
+		return puretui.MsgServerActionDone{Action: "Reload All", Err: nil}
+	}
+}
+
+// restartAgent stops and restarts the whole launcher (full restart, all agents).
+func (a *Adapter) restartAgent(id string) tea.Cmd {
+	return func() tea.Msg {
+		_ = a.mgr.StopUnified()
+		time.Sleep(500 * time.Millisecond)
+		err := a.mgr.StartUnified()
+		if err == nil {
+			time.Sleep(500 * time.Millisecond)
+		}
+		return puretui.MsgActionDone{AgentID: id, Action: "Restart", Err: err}
 	}
 }