fix(inventory): scale 3D modal with viewport, unify market action row

[ykns3]

Follow-up to #410, addressing @Step7750's review comments.

Modal size — the dialog now scales with the viewport instead of pinning to 1120px, using the same treatment as the market site's screenshot dialog: width follows 90vw, with a height-derived cap that keeps the 16:9 stage at or under 80vh. The side-panel layout (≥1520px) adds its 320px panel to the width budget; the item-strip layout (1168–1519px) adds its 122px strip to the height budget, with a 1120px floor so mid-size screens keep today's size. On a 1440p display the viewer stage grows from 1120×630 to ~1984×1116.

Action row — the CSFloat market action (list button or active listing, mutually exclusive) and the 3D button now share one flex row: the market action keeps the left slot whether the item is listed or not, and the buttons no longer wrap to new lines when there's room. Also adds a bit more gap between the float/paint seed info and the row.

Validation

npm run lint, npm run build, npm run checkformat, npm test (31/31).

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Note

Low Risk
CSS layout and inventory UI composition only; no auth, API, or data-path changes.

Overview
The SkinCraft 3D viewer dialog scales with the viewport instead of staying near a fixed 1120px width: default sizing uses 90vw and a 16:9 cap at 80vh (with dvh fallbacks and a 1920px stage ceiling). Breakpoints for the item strip and side panel fold those chrome dimensions into the width/height budget, use a 1120px floor on mid-width layouts, and drop the hard-coded stage width so the grid can grow with the dialog.

In selected item info, the CSFloat list, active listing, and View in 3D actions share one flex row (listing is no longer rendered below), with stallListing included in when that row appears so listed-only items still show the row. Spacing above the action row is slightly increased.

^{Reviewed by Cursor Bugbot for commit 65e35c4. Bugbot is set up for automated code reviews on this repo. Configure here.}

[Step7750]

Thanks @ykns3 !