feat: add edit code blocks and move previous button to right for better ux

[daniqss]

Pull Request

What does this PR introduce?

Clearly describe what this PR changes or adds.
Add edit code blocks and move previous button to right for better ux

Scope of change

Select the affected area(s):

• Builder (Markdown → HTML)
• Pseudocode Lexer
• Pseudocode Parser / AST
• Interpreter / Runtime
• Debugger (step execution)
• CLI
• Documentation
• Tests

Code Quality Checklist

Please confirm that you have followed the project's quality standards:

• I have run npm run lint, npm run format and fixed any errors.
• I have run ruff check --fix . and ruff format ..
• My commit messages follow the Conventional Commits format.

How has this been tested?

• Manual testing
• Unit tests added/updated
• Existing tests pass
• Verified generated HTML output
• Verified step-by-step debugger behavior
• N/A

Explain briefly what was tested.

Breaking changes?

• No
• Yes (explain below)

If yes, describe:

• What breaks
• Why it breaks
• Migration steps (if needed)

Additional notes

close #42