`gum input` shows second prompt

Describe the bug When running gum input, the prompt line initially appears once, then within ~1 second a duplicate second line appears below it. The cursor only blinks on the second line. After pressing enter, the duplicate line disappears, leaving only the input line.

Steps to reproduce the behavior

1. Run gum input in terminal
2. Observe initial single prompt line
3. Wait ~0.5 second - duplicate second prompt line appears
4. Note that cursor only blinks on second line
5. Press enter - duplicate disappears

Expected behavior A single, stable prompt line should appear immediately and remain throughout the input session. The cursor should blink on that single line only. There is no extra line between prompt and enter submit hint.

Screenshots See attached screenshots showing:

• Image 1: Initial state with single prompt line
• Image 2: Duplicate prompt line appearing (~0.5 second later)
• video demonstration to show the timing and behavior more clearly.

Desktop

• OS: macOS 15.7.1 (Sequoia)
• Terminal: Apple Terminal (xterm-256color)
• gum Version: 0.17.0

Additional context The duplicate line appears to be a rendering/refresh issue. The duplicate prompt shows the same text "Type something..." while the original prompt updates normally. Only the second line is interactive (cursor blinks there). After input submission, the display returns to normal single-line behavior.