Add VS Code for HPC workshop notes and accessibility fixes

[Mwarsame871]

Summary

Adds the “Introduction to Visual Studio Code for HPC” workshop notes under content/notes/vscode-intro.

What changed

• Converted and structured the workshop into Hugo notes pages
• Added _index.md and section pages:
  • overview.md
  • using-ood.md
  • running-and-debugging.md
  • local-ssh.md
  • advanced.md
• Added workshop screenshots under content/notes/vscode-intro/img/
• Replaced the old index.md with _index.md for notes structure
• Applied formatting updates to match RC learning-site note style
• Added accessibility improvements:
  • alt text for figures
  • descriptive link text
  • cleaned tables/code formatting

Verification

• Compared content against the original PowerPoint
• Ran Pa11y on http://localhost:1313/notes/vscode-intro/
• Pa11y result: No issues found