Shortcuts fix

[yutahhhh]

Important

Since this PR touches shortcut handling, so I recommend merging it before the following PRs:

• Add improved chalkboard palette UI Add improved chalkboard palette UI #132
• added font size menu that works added font size menu that works #133

Summary

• Switched chalkboard toggles from '[' / ']' to 'L' / 'P'
• Help dialog is now rendered inside .reveal, making it visible in fullscreen mode
• Help button automatically disappears after 5 seconds when opening the slideshow, if not toggled manually

Changes

rise\packages\application\src\plugins\rise.ts:

• Added a global keyboard handler using
  'document.addEventListener('keydown', (event: KeyboardEvent) => { ... }, true)'
• Updated the help dialog rendering to ensure fullscreen visibility
• Adjusted the auto-hide timer for the help button to 5 seconds

rise\packages\lab\schema\plugin.json:

• Updated the displayed chalkboard download shortcut from \ to D to match actual behavior
• Changed chalkboard toggle shortcuts to L (chalkboard) and P (notes canvas)

Updated Help-Menu

Testing

• Start slideshow in Jupyter
• Verify that the help button in the bottom-left corner disappears after 5 seconds
• Open the help menu by clicking the help button or pressing ?
• Verify that all listed shortcuts work as described

[github-actions]

👈 Launch a Binder on branch QubitCube65/rise/feature%2Fshortcuts-fixed