Improve keyboard navigation in the Schema Editor

[alistair3149]

Follows-up to #616

The Schema Editor's property list now supports basic keyboard navigation (ArrowUp/Down to move selection, Alt+ArrowUp/Down to reorder). This issue tracks additional keyboard improvements to make the editor more accessible and efficient.

Improvements

Property list navigation

• Home/End — jump to first/last property (standard listbox pattern)
• Type-ahead — focus the property starting with the typed character

Actions from the property list

• Delete/Backspace — delete the selected property directly (currently requires Tab → delete button → Enter)
• Enter — move focus from the property list to the editor panel for the selected property

Focus management between list and editor

• Escape — return focus from the editor panel back to the property list

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Written by Claude Code, Opus 4.6. Result of brainstorming with @alistair3149. Context: the NeoWiki codebase and PR #616 implementation.

[JeroenDeDauw]

Might make sense to start with a holistic look at keyboard navigation, including hotkeys