fix(tui): constrain form height to terminal and forward resize events

Forms overflowed past terminal because huh didn't know about the
surrounding chrome (header, footer, padding). Now sets WithHeight()
on every render and forwards WindowSizeMsg during form state.

internal/tui/tui.go

@@ -161,6 +161,10 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 
 	// Form state: forward ALL messages to huh (keys, timers, resize, etc.)
 	if m.state == stateFormSite || m.state == stateFormAlert || m.state == stateFormUser || m.state == stateFormMaint {
+		if wsm, ok := msg.(tea.WindowSizeMsg); ok {
+			m.termWidth = wsm.Width
+			m.termHeight = wsm.Height
+		}
 		if keyMsg, ok := msg.(tea.KeyMsg); ok {
 			if keyMsg.String() == "ctrl+c" {
 				return m, tea.Quit
@@ -703,6 +707,11 @@ func (m Model) View() string {
 			case stateFormMaint:
 				title = "New Maintenance Window"
 			}
+			formHeight := m.termHeight - 7
+			if formHeight < 5 {
+				formHeight = 5
+			}
+			m.huhForm.WithHeight(formHeight)
 			header := titleStyle.Render(title)
 			footer := subtleStyle.Render("\n[Esc] Cancel")
 			return lipgloss.NewStyle().Padding(1, 2).Render(header + "\n\n" + m.huhForm.View() + "\n" + footer)