feat: add back navigation, review step, and error retry to TUI

Implements three UX improvements (TODO #1–#3):

- Back navigation: Esc returns to the previous input step. The Model keeps
  a history stack of input steps (advance/goBack helpers); action/wait
  steps are excluded via isInputStep so back never re-enters a
  side-effecting step. Form values are preserved.
- Review step (StepReview): shows all collected config for confirmation
  before any file is written; Enter installs, Esc edits.
- Retry vs. fix: transient failures (image pull, container run) offer
  "r: tentar novamente" instead of quitting; validation failures route
  back to the relevant form to correct the value.

Adds nav_test.go for the history/navigation logic and updates
README/CLAUDE/docs (incl. docs/TODO.md tracking the remaining ideas).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

internal/tui/view.go

@@ -10,15 +10,33 @@ import (
 
 const (
 	header       = "App do Dono - Instalador Cliente"
-	defaultMsg   = "ctrl+c: sair"
 	anyKeyOutMsg = "qualquer tecla: sair"
-	formMsg      = "tab: próximo campo • enter: confirmar • ctrl+c: sair"
+	retryMsg     = "r: tentar novamente • q: sair"
+	fixMsg       = "qualquer tecla: voltar e corrigir"
+
+	formBase   = "tab: próximo campo • enter: confirmar"
+	ipBase     = "↑/↓: navegar • enter: selecionar"
+	reviewBase = "enter: confirmar e instalar"
 )
 
+// helpFor builds the footer for an input step, appending "esc: voltar" when back
+// navigation is available and always ending with "ctrl+c: sair".
+func (m Model) helpFor(base string) string {
+	parts := []string{}
+	if base != "" {
+		parts = append(parts, base)
+	}
+	if m.canGoBack() {
+		parts = append(parts, "esc: voltar")
+	}
+	parts = append(parts, "ctrl+c: sair")
+	return strings.Join(parts, " • ")
+}
+
 func (m Model) View() tea.View {
 	pad := strings.Repeat(" ", padding)
 	var body string
-	helpMsg := defaultMsg
+	helpMsg := m.helpFor("")
 
 	switch m.currentStep {
 	// Docker stuff
@@ -29,53 +47,65 @@ func (m Model) View() tea.View {
 		helpMsg = anyKeyOutMsg
 	case StepDockerLogin:
 		body = m.loginForm.View()
-		helpMsg = formMsg
+		helpMsg = m.helpFor(formBase)
 	case StepDownloadImage:
 		body = m.viewDownloadImage()
+		if m.downloadDone && m.downloadError != nil {
+			helpMsg = retryMsg
+		}
 
 	// IP Stuff
 	case StepIPQuestion:
 		body = m.viewIPQuestion()
+		helpMsg = m.helpFor(ipBase)
 	case StepWireguardConfig:
 		body = m.wireguardForm.View()
-		helpMsg = formMsg
+		helpMsg = m.helpFor(formBase)
 	case StepGenerateWireguardFile:
 		body = m.viewGenerateFile()
 		if m.finishedFile && m.configFileError != nil {
-			helpMsg = anyKeyOutMsg
+			helpMsg = fixMsg
 		}
 	case StepDownloadWireguard:
 		body = m.viewDownloadImage()
+		if m.downloadDone && m.downloadError != nil {
+			helpMsg = retryMsg
+		}
 	case StepRunWireguard:
 		body = m.viewDockerRun()
 		if m.finishedDockerRun && m.dockerRunError != nil {
-			helpMsg = anyKeyOutMsg
+			helpMsg = retryMsg
 		}
 
 	// App Config Stuff
 	case StepAppConfig:
 		body = m.appForm.View()
-		helpMsg = formMsg
+		helpMsg = m.helpFor(formBase)
 	case StepServerConfig:
 		body = m.serverForm.View()
-		helpMsg = formMsg
+		helpMsg = m.helpFor(formBase)
 	case StepDatabaseConfig:
 		body = m.dbForm.View()
-		helpMsg = formMsg
+		helpMsg = m.helpFor(formBase)
 	case StepCertConfig:
 		body = m.certForm.View()
-		helpMsg = formMsg
+		helpMsg = m.helpFor(formBase)
+
+	// Review
+	case StepReview:
+		body = m.viewReview()
+		helpMsg = m.helpFor(reviewBase)
 
 	// Finalize
 	case StepGenerateFile:
 		body = m.viewGenerateFile()
 		if m.finishedFile && m.configFileError != nil {
-			helpMsg = anyKeyOutMsg
+			helpMsg = fixMsg
 		}
 	case StepRunDocker:
 		body = m.viewDockerRun()
 		if m.finishedDockerRun && m.dockerRunError != nil {
-			helpMsg = anyKeyOutMsg
+			helpMsg = retryMsg
 		}
 	case StepDone:
 		body = m.viewDoneMessage()
@@ -155,7 +185,7 @@ func (m Model) viewDownloadImage() string {
 		errText := dualPad + m.downloadMessage + "\n" + dualPad + m.downloadError.Error()
 		sb.WriteString(ErrorStyle.Width(m.width - (padding * 2)).Align(lipgloss.Left).Render(errText))
 
-		sb.WriteString("\n\n" + pad + "Pressione qualquer tecla para sair.")
+		sb.WriteString("\n\n" + pad + "Pressione 'r' para tentar novamente ou 'q' para sair.")
 	}
 
 	return sb.String()
@@ -187,6 +217,51 @@ func (m Model) viewIPQuestion() string {
 	return sb.String()
 }
 
+func (m Model) viewReview() string {
+	pad := strings.Repeat(" ", padding)
+	cv := m.configValues
+
+	var sb strings.Builder
+	sb.WriteString(pad + "Revise as configurações antes de instalar:\n")
+
+	section := func(title string, rows [][2]string) {
+		sb.WriteString("\n" + pad + TitleStyle.Render(title) + "\n")
+		for _, r := range rows {
+			sb.WriteString(pad + HelpStyle.Render(r[0]+": ") + r[1] + "\n")
+		}
+	}
+
+	if len(cv.Wireguard) > 0 {
+		section("vproxy", [][2]string{
+			{"IP Virtual", cv.Wireguard["vip"]},
+			{"Proxy EDPS", cv.Wireguard["proxy_edps"]},
+			{"MTU", cv.Wireguard["mtu"]},
+			{"Protocolo", cv.Wireguard["proto"]},
+		})
+	}
+
+	section("Aplicação", [][2]string{
+		{"Servidor Central", cv.Application["central_server_url"]},
+		{"Token de Inscrição", cv.Application["enrollment_token"]},
+	})
+	section("Servidor", [][2]string{
+		{"Porta (host)", cv.Server["port"]},
+		{"Timeout", cv.Server["timeout"]},
+		{"Ambiente", cv.Server["environment"]},
+		{"Modo Compatibilidade", cv.Server["seccomp_unconfined"]},
+	})
+	section("Banco de Dados", [][2]string{
+		{"Tipo", cv.Database["database_type"]},
+		{"URL", cv.Database["database_url"]},
+		{"Conexões (máx/mín)", cv.Database["max_conns"] + "/" + cv.Database["min_conns"]},
+	})
+	section("Certificado", [][2]string{
+		{"Diretório", cv.Cert["cert_dir_path"]},
+	})
+
+	return sb.String()
+}
+
 func (m Model) viewGenerateFile() string {
 	pad := strings.Repeat(" ", padding)
 	var sb strings.Builder
@@ -205,7 +280,7 @@ func (m Model) viewGenerateFile() string {
 			errText := dualPad + m.configFileError.Error()
 			sb.WriteString(ErrorStyle.Width(m.width - (padding * 2)).Align(lipgloss.Left).Render(errText))
 
-			sb.WriteString("\n\n" + pad + "Tente novamente.")
+			sb.WriteString("\n\n" + pad + "Pressione qualquer tecla para voltar e corrigir os dados.")
 		}
 	}
 
@@ -230,7 +305,7 @@ func (m Model) viewDockerRun() string {
 			errText := dualPad + m.dockerRunError.Error()
 			sb.WriteString(ErrorStyle.Width(m.width - (padding * 2)).Align(lipgloss.Left).Render(errText))
 
-			sb.WriteString("\n\n" + pad + "Tente novamente.")
+			sb.WriteString("\n\n" + pad + "Pressione 'r' para tentar novamente ou 'q' para sair.")
 		}
 	}