fix: forward keyboard events after clicking sprite selector

[Chessing234]

Summary

handleKeyDown ignored any keydown whose event target was not document or document.body. Clicking a sprite in the selector moves focus to that element, so hat blocks like "when space key pressed" stopped receiving key events until focus returned to the document (e.g. green flag).

The guard now only skips editable targets (inputs/textareas/contenteditable), matching the Blockly intent of the original comment.

Fixes scratchfoundation/scratch-gui#10047

Test plan

• Add a "when space key pressed" hat block
• Press space — sprite responds
• Click the sprite in the sprite list — press space again — sprite still responds
• Typing in a Blockly number/text field still goes to the field, not the VM

Made with Cursor

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[Chessing234]

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