Picture canvas command is unnamed and not keyboard reachable

[vvallalta-code]

Summary

The contextual command rendered for a Picture on the design canvas has no accessible name and is removed from the normal tab order. Keyboard and screen-reader users cannot identify or reliably reach the command.

Location

• Package: @paperbits/core
• Shared command template: src/ko/ui/defaultViewManager.html
• The hover-command template currently renders a button with tabindex="-1" and no explicit accessible name.

Expected behavior

The Picture command is keyboard reachable and exposes a meaningful accessible name based on its command metadata.

Acceptance criteria

• Make the Picture canvas command reachable through the supported keyboard interaction model.
• Expose a meaningful accessible name.
• Preserve pointer, focus, and command activation behavior.
• Verify operation with keyboard only and a screen reader.
• Add or update an accessibility regression test where practical.

Tracking: Azure DevOps 30047889