[turinglambdaai]

Problem

The DMG's drag hint is currently an upward-curving arrow. At Finder's fixed icon placements, the arc looks too high and its arrowhead does not line up naturally with the visual drag direction.

Changes

• Replace the curved arc with a horizontal drag cue centered between the application and Applications slots. The icon safe zones stay clear.
• Crucial packaging fix: the installer reads assets/dmg-background.png, not the SVG. Before macOS release and packaged acceptance, render the updated SVG to that PNG using librsvg, and fail early on the wrong PNG dimensions. This also prevents stale PNGs from silently shipping on later artwork changes.
• Document the layout/asset contract.

Validation

• SVG checked for 1320×800 coordinates, icon-safe margins and no overlap with the main text or icons.
• Local CairoSVG render of the proposed geometry reviewed (preview only; packaging uses pinned librsvg).
• macOS packaged acceptance and release workflow execution on a macOS runner.
• Manual Finder inspection (arm64 and x64) on both light/dark appearances.

Does not change project slug, bundle name or runtime behavior. No automatic merge.