[GOOD FIRST ISSUE] Add keyboard shortcuts for common actions

[kiku-jw]

Description

Add keyboard shortcuts to improve productivity and accessibility.

Task

Implement keyboard shortcuts for:

• Ctrl/Cmd + U - Upload files
• Ctrl/Cmd + Enter - Start cleaning
• Ctrl/Cmd + D - Download results
• Ctrl/Cmd + C - Copy results (when available)
• Esc - Cancel/close dialogs

Files to Modify

• docs/assets/app.js - Add keyboard event listeners
• docs/index.html - Add aria-labels for accessibility

Acceptance Criteria

• All shortcuts work correctly
• Shortcuts are documented in UI (tooltip or help section)
• Shortcuts don't conflict with browser defaults
• Accessible (screen reader compatible)

Tips

• Use addEventListener('keydown', ...)
• Check for Ctrl (Windows/Linux) or Cmd (Mac)
• Test with different browsers

[roshninaktode]

Hi @kiku-jw I would like to work on this issue. Could you please assign this issue to me ?

[kiku-jw]

@roshninaktode Sure, my friend!