fix: allow deleting walls and slabs via floating action menu

[nnhhoang]

Summary

• Walls and slabs were excluded from ALLOWED_TYPES in FloatingActionMenu, so no delete UI appeared when selecting them
• Added wall and slab to the allowed types with a new DELETE_ONLY_TYPES list
• Made onMove/onDuplicate optional in NodeActionMenu so structural elements show only the delete button
• Move/duplicate remain available for items, doors, windows, roofs as before

Closes #156

Test plan

• Draw a wall, select it — floating menu shows delete-only button
• Existing behavior preserved (doors/items still show move/duplicate/delete)
• Lint passes (bun run check — 0 issues)
• No new type errors introduced

[kleenkanteen]

@nnhhoang you should add a vid of the full flow btw

[nnhhoang]

@kleenkanteen here is the flow
Select a wall or slab (V → click), then delete it using the floating trash icon or Delete key.

[Aymericr]

Thanks for the PR.
This looks fine, although the deleting action from the floating menu was intended to be click to activate and then click to delete on the canvas, similar to the sledge hammer in The Sims.

moving.while.holding.tool.-.sledgehammer.mp4