feat: lift a graph node on hover

[aaaaahaaaaa]

What

Collapsed catalog graph cards (asset, source, source type) now lift 2px under the cursor, with a shadow step.

• The top card and the folded CardStack layers under it carry the same transform, so a stack travels as one object and the peek under it stays exactly as it looks at rest.
• Only the floor of the stack deepens its shadow, i.e. the one card actually casting onto the canvas: the deepest folded layer when there is one, otherwise the card itself. The shadows between the folded layers stay put.
• prefers-reduced-motion: reduce keeps the shadow step and pins the lift.

Why

The canvas gave no feedback on what the pointer was over. The cards already read as physical objects (elevation tokens, a folded deck peeking out below a collapsed container), so a small lift is the cheapest thing that makes them feel picked out without adding chrome.

Notes for review

• The hover triggers from a new .graph-node class on each node root, not from the card. Two reasons: the layers are siblings of the card, so a card-scoped :hover cannot reach them; and the corner badges sit over the card but outside it, so crossing one used to drop the hover and flicker.
• Expanded containers sit it out. graph-raise is only applied while collapsed: an expanded source or type group holds its members as separate VueFlow nodes, which would not travel with the frame.
• Edge endpoints do not follow the 2px shift — VueFlow draws them from stored handle bounds. At this amplitude the edge still meets the card, and it is the reason the travel is small rather than dramatic.
• The fan adds nothing to layout, but a hovered card reaches ~2px higher against a 20px node gap.
• RunNode (the compact run-graph node) is untouched: it carries its own bespoke shadow and is not part of this card system.

New tokens: --graph-card-shadow-raised, --graph-asset-shadow-raised, --graph-layer-shadow-raised, defined for both themes.

Verification

pnpm run lint and pnpm exec nuxt typecheck pass (4 pre-existing warnings in unrelated files). Not verified in a browser on my side, so the amplitudes are a judgement call and worth a look while reviewing.

By Digitl