Update tui error handling

- Allow each view to position error banners where they choose
- Add global 'esc' key handler to dismiss errors

pkg/tui/views/chat/chat.go

@@ -83,6 +83,7 @@ type Model struct {
 	stopSignal      chan struct{}
 	chatReplyChunks chan provider.Chunk
 	persistence     bool // whether we will save new messages in the conversation
+	promptCaching   bool // whether prompt caching is enabled
 
 	// UI state
 	focus          focusState

pkg/tui/views/chat/view.go

@@ -245,7 +245,7 @@ func (m *Model) conversationMessagesView() string {
 	return sb.String()
 }
 
-func (m *Model) Content(width, height int) string {
+func (m *Model) Content(width, height int, errors string) string {
 	// calculate clamped input height to accomodate input text
 	// minimum 4 lines, maximum half of content area
 	inputHeight := max(4, min(height/2, m.input.LineCount()))
@@ -255,7 +255,15 @@ func (m *Model) Content(width, height int) string {
 	// remaining height towards content
 	m.content.Width, m.content.Height = width, height-tuiutil.Height(input)
 	content := m.content.View()
-	return lipgloss.JoinVertical(lipgloss.Left, content, input)
+
+	var sections []string
+	if errors != "" {
+		sections = []string{content, errors, input}
+	} else {
+		sections = []string{content, input}
+	}
+
+	return lipgloss.JoinVertical(lipgloss.Left, sections...)
 }
 
 func (m *Model) Header(width int) string {