feat(ui): add tabbed forms with height validation

- Implement General/Advanced tabs for add/edit forms
- Add terminal height detection with user-friendly warnings
- Add Ctrl+J/K tab navigation and SSH RemoteCommand/RequestTTY fields

internal/ui/edit_form.go

@@ -284,10 +284,10 @@ func (m *editFormModel) handleEditNavigation(key string) tea.Cmd {
 		}
 
 		if m.focused >= len(m.hostInputs) {
-			// Move to properties area, keep current tab
+			// Move to properties area, first tab
 			m.focusArea = focusAreaProperties
-			// Keep the current tab instead of forcing it to 0
-			m.focused = m.getFirstPropertyForTab(m.currentTab)
+			m.currentTab = 0
+			m.focused = m.getFirstPropertyForTab(0)
 		} else if m.focused < 0 {
 			m.focused = len(m.hostInputs) - 1
 		}