feat: Task 16 — SSH Session Tab (multi-session)

- pkg/tui/session.go — SessionTab with live SSH terminal in a tab
- pkg/tui/messages.go — quitMsg, openSessionMsg, sessionOutputMsg
- pkg/tui/tabs.go — Tab.Close() interface, Add() returns tea.Cmd
- pkg/tui/host_list_tab.go — Enter opens session tab, q quits
- pkg/tui/tui.go — handle openSessionMsg/quitMsg, SetDataDir
- cmd/hostkeeper/tui.go — pass dataDir to model

pkg/tui/tui.go

@@ -23,6 +23,7 @@ type Model struct {
 	SelectedIndex int // deprecated
 	Error         error
 	Quit          bool
+	dataDir       string
 }
 
 // New creates a new TUI model
@@ -47,11 +48,26 @@ func (m *Model) Init() tea.Cmd {
 func (m *Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	switch msg := msg.(type) {
 	case tea.KeyMsg:
-		switch msg.String() {
-		case "ctrl+c", "q":
+		// Only hard quit on ctrl+c (let tabs handle q)
+		if msg.String() == "ctrl+c" {
 			m.Quit = true
 			return m, tea.Quit
 		}
+
+	case quitMsg:
+		m.Quit = true
+		return m, tea.Quit
+
+	case openSessionMsg:
+		tab := NewSessionTab(msg.host, m.dataDir)
+		cmd := m.tabs.Add(tab)
+		return m, cmd
+
+	case sessionDoneMsg:
+		if msg.err != nil {
+			m.Error = msg.err
+		}
+		return m, nil
 	}
 
 	cmd, err := m.tabs.Update(msg)
@@ -94,6 +110,11 @@ func (m *Model) LoadHosts(hosts []*models.Host) {
 	}
 }
 
+// SetDataDir sets the data directory for SSH connections
+func (m *Model) SetDataDir(dir string) {
+	m.dataDir = dir
+}
+
 // TabManager returns the underlying tab manager
 func (m *Model) TabManager() *TabManager {
 	return m.tabs