feat: TUI Host Forms (add/edit) - Task 17

- HostFormTab with textinput fields for all host fields
- Add (Ctrl+N) and Edit (Ctrl+E) from host list
- Save to JSON storage, auto-reload on save
- Esc to cancel, navigable form with keyboard

pkg/tui/tui.go

@@ -1,9 +1,12 @@
 package tui
 
 import (
+	"context"
+
 	tea "github.com/charmbracelet/bubbletea"
 
 	"git.tukangketik.id/swanadiva/hostkeeper/internal/models"
+	"git.tukangketik.id/swanadiva/hostkeeper/pkg/storage"
 )
 
 // Screen represents different TUI screens (deprecated, use tabs)
@@ -63,6 +66,47 @@ func (m *Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		cmd := m.tabs.Add(tab)
 		return m, cmd
 
+	case openHostFormMsg:
+		var tab Tab
+		if msg.editing != nil {
+			tab = NewEditHostFormTab(msg.editing, m.dataDir)
+		} else {
+			tab = NewAddHostFormTab(m.dataDir)
+		}
+		cmd := m.tabs.Add(tab)
+		return m, cmd
+
+	case closeFormMsg:
+		if m.tabs.Len() > 1 {
+			m.tabs.CloseActive()
+		}
+		return m, nil
+
+	case saveHostResultMsg:
+		if msg.err != nil {
+			m.Error = msg.err
+			return m, nil
+		}
+		// Close the form tab, switch back to host list
+		if m.tabs.Len() > 1 {
+			m.tabs.CloseActive()
+		}
+		// Reload hosts
+		return m, func() tea.Msg {
+			store, err := storage.NewJSONStorage(m.dataDir)
+			if err != nil {
+				return nil
+			}
+			hosts, err := store.ListHosts(context.Background())
+			if err != nil {
+				return nil
+			}
+			return loadedHostsMsg{hosts: hosts}
+		}
+
+	case loadedHostsMsg:
+		m.LoadHosts(msg.hosts)
+
 	case sessionDoneMsg:
 		if msg.err != nil {
 			m.Error = msg.err