Keep the card preview visible on small screens

## Problem

DraftOmen's desktop layout degrades badly when the window is displayed on a small screen or resized narrower than an external-monitor layout. Although controls resize, the selected card preview is no longer entirely visible. The column proportions also change in the wrong place: the preview and mana curve should remain together in the right column, while the middle column should absorb more of the width reduction.

## Proposed change

Adjust the responsive QML layout and size constraints so narrower windows preserve the right-column information hierarchy. Keep the selected card preview and mana curve in the right column, scale the card preview to remain fully visible without cropping, and allow the middle column to shrink further before right-column content is lost. Preserve the current useful layout on larger external displays.

## Acceptance Criteria

- [ ] At the application's supported minimum window size, the complete selected card preview remains visible without cropping or leaving the viewport.
- [ ] The card preview and mana curve remain grouped in the right column at narrow and wide window sizes.
- [ ] The middle column can shrink further as the window narrows and does so before the right-column preview becomes clipped or hidden.
- [ ] Narrow-window resizing does not introduce overlapping controls, inaccessible content, or broken interaction targets.
- [ ] The layout transitions continuously while resizing rather than jumping into unusable proportions.
- [ ] Existing external-monitor/wide-window layout behavior remains usable and visually balanced.
- [ ] The actual desktop application is manually verified at the minimum supported size, a representative small-screen size, and a wide external-monitor size.
- [ ] Deterministic UI coverage protects the column ownership and minimum-size behavior where practical.

## Screenshots