Canvas: undo/redo, resize any card, keyboard delete
Added
Undo / redo for the canvas (⌘/Ctrl+Z, ⇧⌘/Ctrl+Z or Ctrl+Y), plus buttons in the
zoom-controls cluster. History spans all three board streams — cards, connectors, and
drawings — up to 20 steps, and coalesces bursty edits (typing, a drag) into single
steps. Another person's live/collab edits are never captured into your history.
New lib/use-canvas-history.ts.
Resize any card. Every card kind is now resizable, not just shapes/frames: a
width handle on each side that reflows the card, so media keep their aspect ratio and
text/info cards re-wrap. Shapes, frames stay two-axis. Wired through the existing
resize → persist path, so resizes are undoable.
Keyboard delete — select a card and press Delete or Backspace to remove it (ignored
while editing text in a card, and in read-only mode). Card deletion stays instant/
un-confirmed by design — undo covers it.
Known follow-up
Undo/redo buttons live in the desktop zoom-controls cluster, which is hidden on mobile;
a mobile home for them (likely the bottom tool bar) is a separate UI decision.
