feat: implement basic TUI framework with host list

- Add Bubble Tea TUI model with Init/Update/View
- Implement host list screen with keyboard navigation (up/down/enter/q)
- Add styled rendering for hosts, selection, tags
- Create hostkeeper tui CLI command
- Add tests for TUI initialization and host loading
- Update project state documentation

pkg/tui/host_list.go

@@ -0,0 +1,84 @@
+package tui
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/charmbracelet/lipgloss"
+
+	"git.tukangketik.id/swanadiva/hostkeeper/internal/models"
+)
+
+var (
+	HostNameStyle   = lipgloss.NewStyle().Foreground(lipgloss.Color("226")).Bold(true)
+	HostDetailStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("245"))
+	SelectedStyle   = lipgloss.NewStyle().Foreground(lipgloss.Color("212")).Background(lipgloss.Color("235")).Padding(0, 1)
+	TagStyle        = lipgloss.NewStyle().Foreground(lipgloss.Color("86"))
+)
+
+// renderHostList renders the host list screen
+func renderHostList(m *Model) string {
+	var b strings.Builder
+
+	b.WriteString(TitleStyle.Render("HOSTKEEPER - SSH Manager"))
+	b.WriteString("\n\n")
+
+	if len(m.Hosts) == 0 {
+		b.WriteString(SubtitleStyle.Render("No hosts found. Add your first host with: hostkeeper add"))
+		b.WriteString("\n\n")
+		b.WriteString(InfoStyle.Render("Press 'q' to quit"))
+		return b.String()
+	}
+
+	for i, host := range m.Hosts {
+		if i == m.SelectedIndex {
+			b.WriteString(renderSelectedHost(host))
+		} else {
+			b.WriteString(renderHost(host))
+		}
+		b.WriteString("\n")
+	}
+
+	b.WriteString("\n")
+	b.WriteString(SubtitleStyle.Render("\u2191\u2193: Navigate | Enter: Connect | q: Quit"))
+
+	return b.String()
+}
+
+// renderHost renders a single host
+func renderHost(host *models.Host) string {
+	var b strings.Builder
+
+	b.WriteString(HostNameStyle.Render(host.Name))
+	b.WriteString("\n")
+
+	details := fmt.Sprintf("   %s@%s:%d", host.Username, host.Hostname, host.Port)
+	b.WriteString(HostDetailStyle.Render(details))
+
+	if len(host.Tags) > 0 {
+		tags := formatTagsForTUI(host.Tags)
+		b.WriteString(" " + TagStyle.Render(tags))
+	}
+
+	return b.String()
+}
+
+// renderSelectedHost renders the selected host with highlight
+func renderSelectedHost(host *models.Host) string {
+	hostText := renderHost(host)
+	return SelectedStyle.Render(hostText)
+}
+
+// formatTagsForTUI formats tags for TUI display
+func formatTagsForTUI(tags []string) string {
+	if len(tags) == 0 {
+		return ""
+	}
+
+	var formatted []string
+	for _, tag := range tags {
+		formatted = append(formatted, "["+tag+"]")
+	}
+
+	return strings.Join(formatted, " ")
+}