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/host_list_tab.go

@@ -62,6 +62,19 @@ func (t *HostListTab) Update(msg tea.Msg) (Tab, tea.Cmd) {
 				}
 			}
 
+		case "ctrl+n":
+			return t, func() tea.Msg {
+				return openHostFormMsg{}
+			}
+
+		case "ctrl+e":
+			if len(t.hosts) > 0 {
+				host := t.hosts[t.selectedIndex]
+				return t, func() tea.Msg {
+					return openHostFormMsg{editing: host}
+				}
+			}
+
 		case "q", "ctrl+c":
 			return t, func() tea.Msg {
 				return quitMsg{}