Save email body to tmp file when error (#64)

* store email body when send fails

* increase error display duration

* feat: save email body

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Co-authored-by: Allan Martinez <martinezallan123@gmail.com>

model.go

@@ -213,7 +213,7 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		m.state = editingFrom
 		m.focusActiveInput()
 		m.err = msg
-		return m, clearErrAfter(5 * time.Second)
+		return m, clearErrAfter(10 * time.Second)
 	case clearErrMsg:
 		m.err = nil
 	case tea.KeyMsg: