Refine and refresh list has no height constraint

[NickCrew]

Description

The list of Refine / Refresh AI-action history items in the Letters (and any other workspace with a refine/refresh list) grows to unbounded height. When many items accumulate — or on a smaller viewport — the list pushes content below it off-screen, breaking the workspace layout.

Acceptance criteria

• The refine/refresh list has a max-height applied and scrolls when items exceed the visible area.
• The content below the list is not pushed out of view when the list is long.
• Existing interactions (item removal, expand/collapse if applicable) work correctly inside the constrained container.
• Visually validated in both light and dark themes.

Notes

• Title fixed from original: "Refinfe" → "Refine".