What

Adds keyboard spatial navigation on the workspace canvas (beam-first).

• Node navigation: Cmd/Ctrl + Option/Alt + Arrow
• Space navigation: Cmd/Ctrl + Option/Alt + Shift + Arrow

Behavior

• Captures these shortcuts even when focus is inside terminal/editor inputs.
• Space navigation clears node selection + editing focus and keeps focus on canvas.
• Node navigation focuses the target node's primary editor.
• Node navigation works across spaces and activates the target space as needed.
• Space navigation anchor is reused only while the last navigated space overlaps the viewport center 40% band; otherwise it recomputes from the current view.

Settings UX

• Keybindings render as keycaps (more scannable than plain text).
• Spatial navigation keybindings are grouped into a compact D-pad preview with a "Customize..." expander.

Verification

• pnpm check
• pnpm test -- --run
• pnpm test:e2e tests/e2e/shortcuts.spec.ts