fix: prevent footer panic on narrow widths and long titles

[jonasws]

Fix footer panic on narrow widths and long titles

Summary

renderFooter crashes the whole TUI with strings: negative Repeat count for some specs / terminal sizes.

The bug

renderFooter builds the footer padding like this:

strings.Repeat(" ", m.width-len(helpText)-len(schemaInfo)-2)

schemaInfo is "<info.title> v<info.version>". When that string is long relative to the terminal width — a long API title, or just a narrow window — the count goes negative, and strings.Repeat panics on a negative count:

Caught panic:

strings: negative Repeat count

...
strings.Repeat(...)
main.Model.renderFooter(...)  view.go:359
main.Model.View(...)          model.go:400

The guard above only zeroes helpText; it never accounts for schemaInfo itself overflowing, so even an empty helpText can't save it.

A second, latent issue: widths are measured with len() (bytes), not display columns. A multi-byte info.title over-counts versus the real terminal width and can drive the count negative even when the text visually fits. renderHeader already uses lipgloss.Width() for this; the footer was inconsistent.

The fix

• Clamp the padding count at 0 before strings.Repeat.
• Measure widths with lipgloss.Width() instead of len(), matching renderHeader and correctly handling Unicode titles.

The sibling renderers (renderEndpoints / renderComponents / renderWebhooks) get their repeat count from calculateContentWidth, which already clamps via max(1, ...), so they were never affected and are left unchanged.

Testing

Added TestFooterRenderNarrowWidth, which drives renderFooter and View() at widths 0, 1, 10, and 40 against a spec with a long title + version. It panics before the fix and passes after.

• go test -v passes
• Existing 3.0 / 3.1 / 3.2 example specs unaffected
• No GIF regeneration — the change is footer padding only, no layout/flow change