[Bug] Mouse wheel scroll in alternate screen mode scrolls too aggressively

Bug Description
Mouse wheel scroll in alternate screen mode is too aggressive — each wheel tick scrolls significantly more than one line, often past the visible viewport, making it impossible to read output that just appeared. Regression: scroll step was noticeably smoother in versions prior to 1.0.100 / 1.0.101.

Environment: macOS, iTerm2, Claude Code v1.0.101 (approx).

Related existing issues: #367, #25682 — both describe alt-screen scroll/scrollback interaction problems, but this specific regression (scroll step size) seems newer.

Expected: one wheel tick = 1–3 lines, like a normal terminal app.
Actual: one wheel tick = half-screen or more, unreadable.

Workaround used: Fn+Up / Fn+Down (PageUp/PageDown) scrolls more controllably, but mouse wheel is unusable.

Environment Info

• Platform: darwin
• Terminal: iTerm.app
• Version: 2.1.101
• Feedback ID: 0a8abf8d-bd55-4091-b216-8ca2dc90c830

Errors

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