Add Essential Keyboard Shortcuts for Better User Experience

### **Description:**

Enhance the Custom Code Editor with essential keyboard shortcuts that users expect in modern code editors. Currently, only Ctrl+Enter is available for running code, but users would benefit from additional shortcuts for common actions like saving, copying, clearing output, and toggling features.

**### What I will do:**

- Add File Operation Shortcuts - Implement Ctrl+S for saving/downloading code and Ctrl+O for importing files
- Add Output Management Shortcuts - Add Ctrl+L for clearing output and Ctrl+C for copying output to clipboard
- Add Editor Control Shortcuts - Implement Ctrl+/ for toggling line numbers and Ctrl+Shift+W for toggling word wrap
- Create Keyboard Shortcuts Help Panel - Add a help modal or tooltip showing all available shortcuts for better discoverability

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This enhancement focuses on improving productivity and user experience by adding the most commonly expected keyboard shortcuts that developers use in code editors, making the Custom Code Editor more professional and efficient to use.

@DhanushNehru I request the maintainer to

- assign me this issue with Hacktoberfest2025 tags

Note - I will be completing the issue in next 3 hours

Thank you. This issue belongs to only author of this issue @stonebanks-js