feat: add bubbletea TUI dashboard for bot server management

Implementa un dashboard interactivo con bubbletea siguiendo el patrón
pure core / impure shell del proyecto:

- pkg/tui/ (PURE): Model, Update, View — solo fmt y strings, cero I/O.
  Update produce Intent[] (datos puros) en vez de side effects.
- shell/tui/ (IMPURE): Adapter convierte Intent[] en tea.Cmd[] con I/O real
  (process management, /proc stats, log tail).
- cmd/dashboard/ (composición): Bridge conecta pure Update con shell Adapter
  usando la Elm Architecture de bubbletea.

Pantallas: Main Menu → Agent List → Agent Actions (start/stop/restart/kill) → Logs.
Navegación: flechas ↑↓, Enter seleccionar, 0 volver, q salir.

Dependencias añadidas: bubbletea, lipgloss.
Actualiza .gitignore para anclar binarios a raíz (/agentctl, /dashboard).
Documenta nuevos scripts en CLAUDE.md.

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

pkg/tui/model.go

@@ -0,0 +1,76 @@
+// Package tui defines the pure TUI model, messages, update, and view.
+// Zero I/O, zero side effects. Only data transformations.
+package tui
+
+// Screen identifies the current TUI screen.
+type Screen int
+
+const (
+	ScreenMain         Screen = iota
+	ScreenAgentList           // list all agents with status
+	ScreenAgentActions        // actions for a selected agent
+	ScreenLogs                // tail log output
+)
+
+// Model is the complete TUI state — pure data.
+type Model struct {
+	Screen       Screen
+	Agents       []AgentView
+	Cursor       int
+	Selected     *AgentView // nil when no agent selected
+	LogLines     []string
+	LogScroll    int
+	StatusMsg    string // flash message ("Started OK", "Error: ...")
+	WindowWidth  int
+	WindowHeight int
+}
+
+// AgentView is a pre-formatted projection of an agent for display.
+type AgentView struct {
+	ID      string
+	Name    string
+	Version string
+	Desc    string
+	Enabled bool
+	Running bool
+	PID     int
+	Uptime  string // formatted: "2h 15m"
+	Memory  string // formatted: "42 MB"
+	CPU     string // formatted: "1.2%"
+	LogSize string // formatted: "350 KB"
+}
+
+// MenuOption represents a selectable menu item.
+type MenuOption struct {
+	Label string
+	Desc  string
+}
+
+// MainMenuOptions returns the options for the main screen.
+func MainMenuOptions() []MenuOption {
+	return []MenuOption{
+		{Label: "Agents", Desc: "Gestionar agentes"},
+		{Label: "Quit", Desc: "Salir"},
+	}
+}
+
+// AgentActionOptions returns the available actions based on agent state.
+func AgentActionOptions(running bool) []MenuOption {
+	if running {
+		return []MenuOption{
+			{Label: "Stop", Desc: "Detener el agente"},
+			{Label: "Restart", Desc: "Reiniciar"},
+			{Label: "Kill", Desc: "SIGKILL forzado"},
+			{Label: "Logs", Desc: "Ver log del agente"},
+		}
+	}
+	return []MenuOption{
+		{Label: "Start", Desc: "Iniciar el agente"},
+		{Label: "Logs", Desc: "Ver log del agente"},
+	}
+}
+
+// InitialModel returns the starting state.
+func InitialModel() Model {
+	return Model{Screen: ScreenMain}
+}